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Optronics Combination Trailer Tail Light - Submersilbe - 7 Function - Square - Driver Side

Optronics Combination Trailer Tail Light - Submersilbe - 7 Function - Square - Driver Side

Item # ST7RB
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Trailer Lights ST7RB - Surface Mount - Optronics
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In Use/Installed

5-1/4" x 4-9/16". Waterproof incandescent combination tail light serves 7 functions: stop, turn, tail, rear reflex, side marker, side reflex, and license plate light. Screw-on lens. Stud mount to trailer. 2-Wire design. (2) 1157 Bulbs. Lowest Prices for the best trailer lights from Optronics. Optronics Combination Trailer Tail Light - Submersilbe - 7 Function - Square - Driver Side part number ST7RB can be ordered online at etrailer.com or call 800-298-8924 for expert service.
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Optronics Trailer Lights - ST7RB

  • Tail Lights
  • Square
  • Incandescent Light
  • Red
  • Surface Mount
  • 5L x 4-1/2W Inch
  • Submersible Lights
  • Optronics
  • Stop/Turn/Tail
  • Side Marker
  • Side Reflector
  • Rear Reflector
  • License Plate

5-1/4" x 4-9/16". Waterproof incandescent combination tail light serves 7 functions: stop, turn, tail, rear reflex, side marker, side reflex, and license plate light. Screw-on lens. Stud mount to trailer. 2-Wire design. (2) 1157 Bulbs.


  • Square incandescent trailer light serves 7 functions for trailers less than 80" wide
    • Stop, Turn, Tail, Rear Reflex, Side Marker, Side Reflex
    • Built-in license plate light illuminates trailer license plate
  • Sealed, waterproof housing and lens unit is submersible
  • Built-in reflector removes the need for a separate reflector
  • Incandescent bulbs are easy to replace
  • Shockproof socket guarantees long bulb life
  • Stud mounts on trailer with included studs
    • Gasket is included to create weathertight seal
  • Wiring design contains lead wires for power and grounds through mounting studs
  • DOT compliant


  • Configuration: driver side
    • Passenger side: ST6RB (sold separately)
  • Dimensions: 5-1/4" long x 4-9/16" wide x 2-7/8" thick
  • Distance between mounting studs (center on center): 2"
  • Number of bulbs: 2
  • Bulb type: 1157
  • Power draw at 12.8V:
    • Stop/turn: 2.5 amps
    • Tail: 1 amps
  • 3-Year warranty

Manufacturer Cross Reference
Light will work as an exact replacement for:
Uni Bond # TL5441L
Wesbar # 3006
Grote # 52632
Peterson # M441L

dimensions of light

Sealed, Waterproof Trailer Light

The waterproof construction of this light makes it ideal for use on trailers that may be submerged, like a boat trailer. The circuit board is sealed, which means that water will not damage the diodes or circuit board.

ST7RB Optronics Incandescent Combination Tail Light for Trailers Under 80" Wide - Submersilbe - 7 Function - Square - Driver Side - Left Hand

Alternate part number: ST-7RB

California residents: click here

Video of Optronics Combination Trailer Tail Light - Submersilbe - 7 Function - Square - Driver Side

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.

Video Transcript for Optronics Submersible Trailer Light Review

Today we're going to be taking a look at the Optronics Submersible Trailer Stop Turn and taillights, suitable for trailers up to 80 inches wide. For the left hand side we've got part number ST7RV. That's going to include our license plate light, making it a 7 function light. For the right side, we've got part number ST6RV. This is going to be a 6 function light, almost identical to the left side without the license plate light, and we'll have a green wire for connecting, rather than the yellow that we have with the left hand side. Here you can see our light, once illuminated, it's going to give us a really nice, full red glow, and that outer edge again instead of it just being wasted space, that acts as a reflector. See here on the bottom, we've got the illumination for our plate.

It's going to shine down and really light it up nicely so we can stay in compliance with any transportation laws. It's really nice and securely mounted, durable design, should give us a good long lasting light. Brake, and our blinker, and our taillight. All right, now our lights offer an incandescent bulb. Those are in a shock proof socket. It's going to give us superior bulb life.

Great thing about them also, their fully submersible so these are going to work out really good for our marine applications, whether it's a boat trailer, a personal watercraft trailer, or even farm use style trailers, or utility trailers, the ones that go down the dusty roads and stuff. It keeps out water, it's also going to keep out that dirt, or that dust that can hold moisture and cause corrosion. The inside of our housing is corrosion resistant. You can see it's going to be about 4 and a half inches wide by about 4 and a half inches tall. The center circular part, that's our lens, and it offers a nice reflector all the way around there so even when our trailer's just sitting in the driveway it'll still be good and visible. Same thing for our turn signal, the bulb's going to be right inside that middle housing.

The lens itself is going to be about 2 and 3/4 of an inch by 2 inches. All the way around that rectangular opening, that's going to be fully reflective. Again, giving us really nice vision of it even when the lights aren't on. Our studs are set on 2 inch centers making this a very common application. We've got our flange nuts here on the back.

The washers are going to be sandwiched between the light and our trailer. Our flange nuts will come down on making the ground, eliminating the one extra wire that we sometimes have. Installation of these lights is really quite simple. We're going to take our light, we've got our foam pad on there. It's going to slide right into the mounting location. On the backside we'll add a flat washer to each of the studs and then we'll thread on our nuts. Now it's just a matter of snugging those down and we're ready to make our connections with our wires. To make our connections we want to get the left side turn and brake signal wire. On our trailer it's yellow, which is pretty common. Yours maybe a different color. We want to get our taillight signal on our trailer, it's brown. Yours maybe a different color, but once you figure out what's what, the brown wire, or the taillight signal, that's going to go to the brown wire coming from our light, and our stop and our blinker signal, that's going to go to our yellow wire. Now I'm going to be using part number DW05744, so 14-16 gauge heat shrink butt connector. Then using these especially on the trailers, they really give us superior moisture protection. We don't have to worry about any moisture getting in there and causing corrosion on our wires, which is nice. I'm going to use the heat source, I'm going to use the lighter. You can also use a heat gun, or a mini torch, and just get those shrink down. Once I squeeze that wire then that wire looks like it kind of magnifies and then it's a little bit of gel that comes out of the end there, that's the glue, or the sealant that makes sure that moisture stays out. All right. Then, either back through your wire loom, or whatever you need to do to tidy up your wires, you just want to take as much slack as you can in from your light. We really don't want that to be hanging down to where it might get caught on something. Now we're ready to hook up to our trailer and we can test it out and see how it works. With everything working properly, that's going to complete our installation of the Optronics Submersible Trailer Stop Turn and Taillights, part number ST7RV for the left side, and part number ST6RV for the right.

Customer Reviews

Optronics Combination Trailer Tail Light - Submersilbe - 7 Function - Square - Driver Side - ST7RB

Average Customer Rating:  4.8 out of 5 stars   (56 Customer Reviews)

5-1/4" x 4-9/16". Waterproof incandescent combination tail light serves 7 functions: stop, turn, tail, rear reflex, side marker, side reflex, and license plate light. Screw-on lens. Stud mount to trailer. 2-Wire design. (2) 1157 Bulbs.


Etrailer's service was excellent, I got the lights on time as promised. These submersible lights are a good fit replacement and istallation was simple. 35633


I haven't installed these yet on my motorcycle trailer but they are a good match for the ones I'm replacing. Quality appears to be good, especially for the price. However, these are advertised as waterproof, submersible lights yet each one has 2 open holes in the back with no seals - one where the wires go in and a lower one that appears to be a drain. I picked submersibles to minimize corrosion inside. 592673


Easy to install, works as designed, affordable, and delivered within a reasonable time. I have not submerged the lights yet, so the jury is still out...but other than that, they're great. 223148

One of the lamps does not work properly...and the amount of use it has had is minimal while also being stored inside.
Petosh - 08/30/2016



Fast service, excellent product. I have already installed it and it is working great. Can't say enough about this company and I have used them before--always excellent service. A+++++++++ 218273

Still working great after a year!
Dave - 08/09/2016



Just what I needed. 119684


I often buy over the internet and am often hesitant to do so because the product was not described in detail. This was not the case with the taillight I recently purchased. The item was well described and was exactly what I wanted. Fast delivery. I will do future business with etrailer.com 95584


Looks like it will work great wont get it put on till spring, its going on my boat trailer. Getting tired of bout getting run over, thanks for the great service, if i need anything else i will go here first, 235055


I was greatly pleased with the web site, the product itself(an exact replacement of the lights I needed), the price and the professional way the order was processed and handled. I highly recommend using Etrailer for your next purchase. 73697


Parts purchased 1/2, shipped 1/3, arrived 1/7 in one large, well packed box. Everything as ordered. Etrailer has excellent prices, shipping and handling. 168324

Its all working well and Im pleased with the quality.Thanks
Pete - 01/18/2016



I found these taillights to be an excellent value. I have had them on my trailer for a while now and they have performed very well. I had to order a replacement due to the boat ramming into it when I was reloading the boat onto the trailer after a recent fishing trip. etrailer is very good to deal with. 154299


So far so good. I have used light for one season. Just replaced second old light with one of these. 547652


Fast delivery, 2 days. Installed the lights today and working great! 399341

Still working great, I have no regrets of purchasing these lights.
Doug O - 06/26/2018



Great product selection, description;, prompt service and excellent follow-up and I would use these people any time. Also excellent prices. 167749


I haven't tried the submersible aspects of these lights yet, but installation was a breeze, everything worked, and they look good. Especially nice about dealing with etrailer.com were good website, very reasonable shipping charges, excellent communications (several of them), and quick shipping. This is a very good company to do business with. Highly recommended. 12775


I put these lights on my John boat trailer a year ago and launch my boat in salt water often and they still work as good as the day I installed them. Etrailer shipped them fast and have very good customer service, I can say I am impressed with their service and will be ordering from them again. 607311


As Advertised... As always...Great site … Great product 708480


Just what I needed 704584


Just what I expected, great fit 666202


I know I'm breaking them extremely fast, so for me it is a good choice. just 7$. 665843


GREAT ...even better service!! I highly recommend etrailer!!! Shipped to me under the three day window. Thank you! 661223


All is well and good, thank you. Product very satisfactory, 605465


great price, wish they had a passenger side light too! 595881


These trailer lights are very well made and inexpensive to boot. They installed very easily and look very good. 567160


easy to hook up to existing wires, works like a charm! 505838


Great service...the part was correct the first time....keep up the good work 502168

Show More Reviews

Ask the Experts about this Optronics Trailer Lights

  • Do You Have a Replacement Tail Light For My Carson Trailer
    This taillight should work on your Carson trailer as long as the original mounting holes are 2 inches on center and your mount is steel and attached directly to the trailers frame. This light gets the ground connection through the trailer frame and mounting studs. The yellow wire goes to the left turn/brake wire and the brown wire is for the taillights. If the light on your trailer is not attached to the trailer frame and needs a ground wire attached to the frame or ran to the front...
    view full answer...
  • Troubleshooting No Running Lights On Boat Trailer
    I recommend to first check that your 4-way connector has a good connection with the connector on the trailer. If the 4-way connector on the vehicle has any rust or corrosion on the pins you can lightly sand that off with a fine grit sandpaper. It is also a good idea to check for bent pins on the connector. If your connectors are in good shape, I recommend to check the ground on the 4-way and make sure it is attached to a clean bare metal surface of the vehicle frame. If the ground is...
    view full answer...
  • Can Bulb on Optronics 7-Function Light # ST7RB Be Replaced
    In order to tell you for sure if the light bulb can be replaced we will need to determine exactly which light that you have. You will want to look on the actual light housing for the manufacture name and model number. Trailer light lens can typically be used on multiple different light housings so with just the numbers from lens I can not be certain as to which light you have. If you do determine that you have the Optronics Submersible, Trailer Stop, Turn, Tail and License Plate Light,...
    view full answer...
  • How Can I Get Trailer Lights to Flash when Disconnected from Truck
    If your trailer happens to have LED lights on it then what you could do is use a separate car battery and a couple of Custer strobe drivers, # STR-MRLY or # STR-QRLY, and connect the output wires to the trailer connector wires as needed. This driver is only rated for 420 milliamps though so only about 2 LED lights be driver would work. And if the trailer has regular incandescent lights then it will not work because the power draw would be too high. Another simple option, battery powered...
    view full answer...
  • Trailer Tail Light Protector and Matching Tail Lights
    The light guard # LG440NP is designed to fit Peterson square tail lights # 432200 for the right and # 432400 for the left. A license plate light is still a good idea because you never know where you might tow the trailer! You could also use submersible lights # ST7RB for the left and # ST6RB for the right. And you might be interested in aluminum tread plate light protector # CE26051A. Since it is aluminum it will not corrode like steel.
    view full answer...
  • Can Trailer Running Lights be Powered Off of a Battery When Not Connected to a Trailer
    I do have a way that you can wire the lights on the trailer so that they will come on when connected to the tow vehicle or off of a battery on the trailer. What you will need to do is add 2 diodes, # RM-792, to the wiring set up. You will also need a switch, # D16740, and a wiring installation kit # 55151. I have included a diagram of how this should all be wired. Basically the wiring to the light will come from 2 sources; the trailer connector, and the battery via a switch. The diode...
    view full answer...
  • Boat Trailer Tail Lights Stopped Working After Backing Trailer in Water
    There is a subtle difference between submersible lights like # ST7RB and completely sealed lights. Submersible lights will let in water but will allow it to drain out. Sealed lights will keep water out and as such are also submersible. Part of the problem is that you really need to disconnect the trailer wiring prior to submerging the trailer in the water since the light is not sealed and the connection splices are not water tight. The brake light/turn signal functions not working...
    view full answer...
  • Replacement Options for a Sealed Trailer Light with a Bad Bulb
    The Peterson 440 series trailer lights typically have 4 screws at each of the corners of the lens that allow you to remove the lens and replace the bulb. It may be possible that you have a sealed version of these lights, in which case the bulb is likely not replaceable without breaking the seal between the lens and the light housing. You will likely be better off replacing the tail lights. For a submersible light with a replaceable bulb and lens that is similar to the Peterson 440 series...
    view full answer...
  • How to Power Trailer Lights from Battery when Not Connected to Tow Vehicle
    A battery isolator will cut off power once the solenoid is energized from another source. Diodes on the other hand only allow power to flow one way. What you will need to do is run a power wire or wires from the positive battery terminal on a trailer battery to a switch such as # PK34571. Then you would run another wire from the switch to a diode # RM-690. Then run a wire from the diode to the trailer wiring for the lights you want to power. Depending on what lights you want to use...
    view full answer...
  • Right Side Trailer Lights Not Working After Installing a Wiring Harness on 2011 Mitsubishi Endeavor
    A poor ground connection could cause one side of your trailer lights not to work. I would start by checking the ground connections on the trailer since the wiring harness that you purchased does not have a separate ground wire. The ground connections on your trailer should be clean and corrosion free. Check the ground connection for the trailer connector as well as the grounds for the trailer lights. You could also inspect the trailer side connector for any corrosion and clean or replace...
    view full answer...
  • Replacement Bulb for Peterson Trailer Taillight Assembly V540
    It looks like you have the Peterson version of the Optronics Lights # ST6RB and # ST7RB. For either of these lights, the correct replacement bulb will be # A1157B. Replacing the bulb is pretty easy actually. Just remove the 4 screws from the lens of the light assembly and the bulb will be right there for you to twist out of its socket.
    view full answer...
  • How to Use Trailer Running Lights as Accent Lights When Connected to Campground 110 Volt Electric
    To use your trailer running lights as accent lights with the trailer plugged into 110 volts, you will need to wire in a 110 volt to 12 volt converter to the 4-Way connector on your trailer. With your trailer plugged into the campground electric, you will plug the converter into an 110 volt outlet on the trailer. Next, from the 12 volt outlet side of the converter you will need to wire a ground wire to the white (ground wire) on your 4-Way connector. Then, run a wire from the 12 volt...
    view full answer...
  • Recommended Boat Trailer Lights For Shorelandr Brand Trailer
    We don't have the exact lights, but we do have similar ones. Without knowing all of the sizes, it is really difficult to make a recommendation. I did find the tail light dimensions, so for those I recommend the Submersible, Trailer Stop, Turn and Tail Light, 6-Function, Right Hand # ST6RB and Submersible, Trailer Stop, Turn, Tail and License Plate Light, 7-Function, Left Hand # ST7RB. For clearance lights, I've linked the page to help. Side marker lights are in this same category....
    view full answer...
  • Recommendation for Replacement Submersible Trailer Lights that Ground through Mounting Hardware
    For a similar assembly to the Wesbar units you currently have installed on your trailer, I recommend looking at the Optronics Submersible Assembly # ST6RB for the Right Hand and # ST7RB for the Left Hand. These lights measure 5-17/64 inches long, 4-9/16 inches wide and 2-7/8 inches deep. These particular assemblies are designed to be corrosion resistant and includes a gasket that will create a weathertight seal. A shockproof socket will guarantee a long bulb life and the wiring design,...
    view full answer...
  • What are the Correct Replacement Bulbs for Optronics Trailer Lights # ST6RB and # ST7RB
    It looks like you have Optronics Lights # ST6RB and # ST7RB. For either of these lights, the correct replacement bulb will be # A1157B that you have referenced and # 30-90-194 for the side light. Trailer lights are a 2-wire system. This means that they have combined stop and turn signals on the same bulb. If the lights do not blink with the turn signals, you may need to change the running light wire with the stop/turn signal wires. Use a circuit tester like # 40376 to test the trailer...
    view full answer...
  • Recommendation for Sealed Lights on a PWC Trailer that is Launched in Salt Water
    I would recommend going with LED lights that have sealed units in them like the LED Submersible Trailer Stop, Turn and Tail Light, item # STL8RB and the # STL9RB, for your trailer. The inside of these lights are fully sealed for corrosion protection and you would only have to worry about sealing connections where the wires are spliced into the trailer wiring. For sealing the wire connections you can use Liquid Electrical Tape, item # SWC50122.
    view full answer...
  • Will Optronics Submersible Trailer Light ST6RB Work on Malone Kayak Trailer
    The Submersible Trailer Stop, Turn, and Tail Light # ST6RB that you referenced is a great choice to replace the existing lights on your Malone Kayak Trailer. The light housing is designed to allow water to flow in and back out of the housing while being submerged. This light has 6 functions: stop, turn, tail, rear reflex, side marker, and side reflex, and will mount on studs with 2 inch centers. For the left-hand version of this light you will want # ST7RB. For a similarly sized light...
    view full answer...
  • Wire Gauge of 25 Foot Harness Included with Submersible, Under 80 Inch Tail Light Kit
    Optronics uses small 20 gauge wiring for their 4-Way wiring harnesses so it would be even smaller than 18. In order to get 14 gauge wires I recommend # DW04923-1 which is sold by the foot. Each of the wires in it are 14 gauge. Then you would just need the lights, # ST6RB and # ST7RB, 2 of # MC36AB, and license plate bracket # LP10SB. And for the additional clips, connectors, ties and other parts I recommend the wiring kit # HM51020.
    view full answer...
  • Recommended Inexpensive Submersible Trailer Tail Lights
    I can highly recommend the lamps I use on my PWC trailer, # ST6RB and ST7RB. The lamps are submersible, inexpensive and durable. They are also available in an LED version, # STL8RB and STL9RB. The LED versions are obviously quite a bit more expensive, but they are brighter and only use a fraction of the power that a comparable incandescent bulb would. LEDs do not burn out, you will never have to replace a bulb.
    view full answer...

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Info for this part was:

Expert Research:
Robert G
Expert Research:
Michael H
Expert Research:
Jeff D
Expert Research:
John H
Updated by:
Adele M
Updated by:
Laura H
Updated by:
Sarah W
Updated by:
Brian T
Video by:
Kathleen M
Installed by:
Cole B
Installed by:
Randy B
Video Edited:
Chris R

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