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Optronics Trailer Tail Light - Stop, Turn, Tail - Submersible - Incandescent - Round - Red Lens

Optronics Trailer Tail Light - Stop, Turn, Tail - Submersible - Incandescent - Round - Red Lens

Item # ST45RB
Our Price: $7.93
Trailer Lights
Shipping Weight: 0.24 lbs
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4-1/4" Diameter round. Waterproof trailer light functions as a stop, tail, and turn signal light when properly mounted. Shock-proof socket protects incandescent bulb. Flush mount with grommet (sold separately). Accepts 3-prong plug. Great Prices for the best trailer lights from Optronics. Optronics Trailer Tail Light - Stop, Turn, Tail - Submersible - Incandescent - Round - Red Lens part number ST45RB can be ordered online at or call 1-800-940-8924 for expert service.
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Optronics Trailer Lights - ST45RB

  • Tail Lights
  • Round
  • Incandescent Light
  • Red
  • 4-1/4 Inch Diameter
  • Recessed Mount
  • Stop/Turn/Tail
  • Submersible Lights
  • Optronics

4-1/4" Diameter round. Waterproof trailer light functions as a stop, tail, and turn signal light when properly mounted. Shock-proof socket protects incandescent bulb. Flush mount with grommet (sold separately). Accepts 3-prong plug.


  • Red trailer light serves 3 functions when properly mounted
    • Stop light
    • Tail light
    • Turn signal light
  • Sonically sealed, waterproof housing and lens unit is submersible
  • Shock-proof socket protects the bulb
  • Durable polycarbonate lens and housing
  • Red lens
  • Flush mount with grommet (A45GB - sold separately)
  • Accepts industry standard 3-prong plug (A45PB or A47PB - both sold separately)
  • DOT compliant


  • Overall dimensions: 4-1/4" diameter x 2-1/16" thick
  • Power draw at 12.8V:
    • Stop/turn: 2.4 amps
    • Tail: 0.49 amps
  • 3-Year warranty

Manufacturer Cross Reference
Light will work as an exact replacement for:

  • Uni Bond # SE4000R
  • Wesbar # 423541
  • Truck Lite # 40282R/40202R
  • Grote # 52922
  • Peterson # 426R
  • Bargman # 40-01-001

Optronics ST45 Series 4 Inch Round Tail Light

Sonically 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 housing and lens are sonically sealed together to create a single unit, which means that water will not get into the light and damage the diodes or circuit board.

Recessed-Mount Light

Recessed mount light

Recessed-mount trailer lights install underneath a housing or a grommet (A45GB - sold separately). These lights will extend into the mounting surface and require that a hole be cut into your trailer.

ST45RB Optronics Trailer Tail Light - Stop, Turn, Tail - Waterproof - Incandescent - 1 Bulb - Round - Red Lens

Alternate part number: ST-45RB

California residents: click here

Customer Reviews

Optronics Trailer Tail Light - Stop, Turn, Tail - Submersible - Incandescent - Round - Red Lens - ST45RB

Average Customer Rating:  4.8 out of 5 stars   (170 Customer Reviews)

4-1/4" Diameter round. Waterproof trailer light functions as a stop, tail, and turn signal light when properly mounted. Shock-proof socket protects incandescent bulb. Flush mount with grommet (sold separately). Accepts 3-prong plug.


Your service was excellent. The trailer light I needed was well described at your website. The ordering process was easy. You sent an email notice that the order was processed and shipped on the same day - wow. It arrived quickly and is now installed. It works perfectly as expected.
Much appreciated...

GZ Westcliffe, Colorado

Gary Z.


Thanks for your follow up. I appreciate dealing with a customer - concerned company such as yours. Running a ranch, I do have an assortment of old trailers which from time to time need replacement parts.You will alway have my business as meager as it is.The product is fineā€¦Thanks, and best wishes for your business success.


This is a great looking classic trailer brake/turn light, which I used on my homebuilt woody teardrop. The lamp is quick and easy to change . . just pop it out from the base, unplug it, and plug in the new one. Etrailer, as always, does a great job providing all the parts a builder needs!


Optronics ST45RB is perfrect replacement for GLO-BRITE 9541.


Quick delivery. Excellent customer serv ice.


It was an exact fit. Well worth the mon ey.


Hi guys,
I'm usually the one answering
These guys are great! My client emailed the link & told me to order these for our horse trailers.
They've held up, to the point, we're not even close to needing to replace them.
We haul quite a bit. These lights have been tried & true, day & night.
When you're hauling a lot of livestock, you want people that have no clue what that entails, to see your lights well before they get near your livestock ; these lights do the job perfect!
We've outfitted 3 separate trailers with this company. We restored wires, lights, & pretty much everything along those lines ;from a 2 horse, to a large stock, & a gooseneck. All the parts come quickly, are all there, & work & fit great. What more can you ask for?!


Product seemed to work very good, but I was unable to get it mounted on my trailer. I must have not ordered the right light or extra materials for mounting. Other than that, good product.

Etrailer Expert

Patrick B.


There is a grommet listed in the related products section on the right side of this page. The grommet will be needed if you do not already have one or the old one is no longer usable.There is a bracket also available if this light is not going into a pre-existing mounting hole.


For the price I can hardly complain, but one of the two already lost it's parking/running light 2-3 months ago, and they've been installed less than a year. I use my lights maybe 10 min/day, only on early mornings on the way to work. I've also used the Peterson brand lights, but after replacing those multiple times for the brake lamps going out I decided I might as well try something cheaper if I was only going to get junk anyways. I guess I'll try LEDs next.


This taillight was very difficult to find - it went on a tow dolly that I tow behind my motorhome. etrailer got it to me on time for a tour of the National Parks in Utah.
It was difficult to install in the rubber grommet but once installed worked well the entire trip from GA and back! etrailer solved my problem and expeditiously!


We had a horrible hail storm and it completely wrecked our new travel trailer. We could live with the hail damage until we could get it in for repair but what we couldn't live w/o was the tail light. I drove all the way down to the place I bought the trailer & they said they would order it for me. I asked how long? he said 'a week or two'. I said I needed it in a week because we were camping again the next weekend. Come Tuesday, I called & he said "o...I need to call the manufacturer" I knew at that point I could not rely on the parts department. I got on-line & found the exact light I needed. The pictures front & side helped a lot because there are so many lights to choose from....I paid for 2 day shipping & it was here before our camp trip...Very fast reliable service. Thats what customer service should be. It fit perfectly & worked properly.
Thanks so much! will use this company again in the future if needed!


we bought an odd brand and older horse trailer and it had a tail light out. figured we would never find a replacement. I googled the name and etrailer popped up. the photos of the light, how it plugged in, what models it was compatible with etc, made it so simple for this 68 yr old non mechanical woman to find the right light. and the price was amazingly low. So, yes, I am very pleased and would recommend them to everyone!!


etrailer rocks !!
Quick delivery, product
exactly what I expected. Could not have been better.
Taillight for a pu truck utility bed, unable to talk with the parts department of the manufacturer who is relatively local, I guess they must be VERY busy, just googled the part # off the old unit and etrailer had it listed - bada bing - new unit at the shop in two days!! standard delivery. Will always look here first for parts.


etrailer is the best online source for RV related parts. Can't beat their prices and service. The tail lights I got are perfect, well packaged, promptly shipped. I will always go to etrailer for RV parts.


I am very happy with every part of my experience buying from The customer service was excellent, the product was perfect and I could not find anything like it locally. I highly recommend this company. Best of all the price was far lower than anywhere else on the internet! Oh one more thing. They even hade demo videos of the product so I could see it in action! Icing on the cake! Thanks etrailer.


I ordered new lights for my horse trailer. They are a perfect match, great price and arrived in 2 days via USPS at no charge. This was a great experience and I would reccomend etrailer to anyone needing parts for their trailers.
Good job guys!


Just got the camper home from a work trip. ordere before I finished the job, the wife brought them to me
fast delivery very good price.
couldnt find them local
I got a pair of nerf bars s.s./w lights early summer
Nice Very Nice also had fast shipment on those
thats why I came back. Very good vendor
Thanks Roy


the lights that i ordered require a plug to connect them. nothing in the advertisement let me know i needed the plug so here i am out the cost of the lights and still cannot finish my trailer. not worth returning and i was running out of time, so i went to the local retailer and bought a complete set. i have had great luck with etrailer in the past, but i guess this deal was just too good to be true. threw them in the trash.


The product was all I could hope for and the service from etrailer was superb. I placed an online order for one bulb and then decided the next day to change to two and called them. No problem they updated the order and I received both bulbs in three days. This is the first review I have ever written but the price and service deserve to be noted


Lights worked great on a 5th wheel camper. Replaced all four. So the brightness was the same. Prompt shipment. Great deal. Thank you.


The order I placed for a 4" round trailer stop/turn light was received very promptly. Price was very reasonable and the order process was easy. I recommend for all your trailer and vehicle needs.

Thank You


I am a new RV owner, and discovered 1 taillight not working on recently purchased dolly trailer. After finding your web-site in magazine, and ordering replacement lens, was pleasantly surprised on the quick response and delivery of replacement.


I have used etrailer before to fix lights on my old horse trailer. Info on the website gave me confidence I was ordering the right thing and the light came quickly and was exactly what I needed


Product was an exact replacement for the tail light for the Yakima trailer and 1/3 the price of the dealer. Arrived promptly. Very happy with your service.


I looked in all the local auto supply stores for this unit with no luck. I didn't even know what it was called, but I found it on in no time at all. Shipping was fast and it was exactly what I needed.


super fast shipping, great prices, best place for shopping for parts for your trailer, I have used them several times and always been very satisfied with fast shipping and the products I have bought!!! Right on you guys!!! The best!!!

Show More Reviews

See what our Experts say about this Optronics Trailer Lights

  • What Causes Dim Brake Lights on Yakima Rack and Roll Trailer
    With a trailer that is made of aluminum, you can experience grounding issues. Since you indicated that the light appears to work for the functions, but is dim when applying the brakes, I think this may be the problem. Due to vibration when in use, the wires can become loose, causing varied issues. I would first make sure all of the wire connections are secure on the trailer. You might want to check the ground wire connections on the trailer. Make certain the ground wire (usually white)...
    view full answer...
  • Can Bulb be Replaced on Optronics Trailer Tail Light # ST45RB
    I spoke with my contact at Optronics and he said that the Trailer Tail Light # ST45RB is a sonically sealed complete unit and the bulb cannot actually be replaced by itself. If the bulb goes out a new # ST45RB will be needed to replace it. I have attached a short video demonstration on this light that you can also check out.
    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...
  • Availability of a Round 4 inch Diameter Flush Mounted Clearance Light
    The part # ST45RB is a flush mounted red trailer light that is 4 inches in diameter. The part # STL42RB is also an option. It is LED 4 inch in diameter and has a flange mounted around the outside of it. For more similar options check out the link I attached that has all of the recess mounted 4 inch diameter clearance lights we offer.
    view full answer...
  • Replacement Trailer Tail Light for a Glo-Brite 9877-88 LED Tail Light
    I looked up the Glo-Brite light you mentioned. Light # STL90RB is almost exactly the same. It has the same 7 inch diameter and the same 6-1/4 inch hole spacing. It is a little deeper by about 7/16 inches. It also has more diodes, 31, compared to the Glo-Brite with 17. As far as fitting in its place though # STL90RB is the way to go.
    view full answer...
  • Harness Availability for the Sealed, 4
    Yes we do carry the plug/harness for the light part # ST45RB. For that you would want the part # A45PB.
    view full answer...
  • Are the Light Bulbs in the Cargo Carrier Light Kit # 52014 Replaceable Or is a New Light Needed
    The bulbs in the Cargo Carrier Light Kit For 52017 and 52018 Cargo Carriers, item # 52014, are not replaceable because the light housings are factory sealed to keep out water and road grime. The Light itself can be replaced though. Part # ST45RB is the Sealed, 4 inch Round Trailer Stop, Turn and Tail Light, Flush Mount, 3-Function and will replace your existing light.
    view full answer...
  • Troubleshooting Stop/Turn Signal of a Optronics Light part # ST45RB on a Trailer
    It sounds like the problem is in the wiring. If your light is a dual intensity light and both intensities are working with the running lights and brighter with the brake lights then the problem lies in the turn signal circuit most likely on your vehicle. You might test the trailer connector on your tow vehicle with a circuit tester like our part # PTW2993 like the video I attached shows to determine if the wiring of your vehicle is good. If the problem is in the vehicle wiring you will...
    view full answer...
  • Availability of Replacement Tail Light for Cargo Carrier Light Kit
    Yes it is. Part # ST45RB is the Sealed, 4 inch Round Trailer Stop, Turn and Tail Light, Flush Mount, 3-Function and will replace your existing light.
    view full answer...
  • Troubleshooting Trailer Taillights Where Only One Side of Trailer Lights Work
    First thing you should do at this point is test the 4-way of the wiring harness with a circuit tester part # PTW2993 for voltage on all of the right pins when the taillight signals are being applied. Just like in the video I attached. If the voltage checks out there but the trailer lights still don't function right then the problem is on the trailer wiring. That would mean that problem is either due to a ground issue or a short issue. Make sure that the trailer side connector are clean...
    view full answer...
  • How to Remove Tail Light That Has Rivets Holding the Grommet in Place
    It all depends on how the light installs. If it is like the Optronics part # ST45RB that installs with the grommet # A45GB then you should be able to remove it without removing the grommet. You may need access behind the light to do this though. If your tail light is more like the Optronics part # ST40RB though where the grommet is part of the light then you will need to remove the rivets by drilling them out and then use new rivets or even screws to install the new tail light (or the...
    view full answer...
    Image 1 for
  • How Does Trailer Light # ST45RB Mount into Mounting Bracket # BK45BB
    I went out to the warehouse and pulled Optronics Trailer Light, # ST45RB. First, you will need to place the Rubber Grommet, # A45GB, into the mounting bracket, # BK45BB. Next, you will need to press the light until it is seated all the way in the bracket. This last step actually takes some strength as the light is held in place by the grommet. I had to use some lubricate to get the light to seat all the way in the mounting bracket. Once in place, the light will not come out unless it is...
    view full answer...
  • Replacement Round 4-1/4 Inch Grommet Mount Trailer Stop/Turn/Brake Lamps
    The closest lamp we offer to what you describe would be the Optronics # ST45RB. The lamp measures 4-1/4 inches in diameter at its largest, and the lamp installs into a 4-1/2 inch rough opening using the rubber grommet which is available separately as part # A45GB. If the 4.25 inch mounting diameter you refer to represents the diameter of the rough opening that the lamp installs in, this lamp will be a bit too large so you'd need to either enlarge the hole by 1/4 of an inch. The 3 pin plug...
    view full answer...
    Image 1 for
  • Availability of LED Replacement for Round Glo-Brite 9541 Light Assembly
    The closest option we have available to your existing round Glo-Brite assemblies (which are no longer made) is the Optronics LED Trailer Tail Light # STL13RFHXB. This assembly has an overall diameter of 5-5/8" and the light face itself measures 4" in diameter. This unit has a standard 3-wire pigtail (not the 3-prong plug) so you would need to hardwire it to your trailer's wiring at the back. The 3 bolt holes are spaced apart by exactly 4-1/4", so you may need to drill some additional...
    view full answer...
  • Availability of 2 Inch Diameter 3-Function Taillight
    There is not a 3 function lamp available that has a 2 inch diameter. DOT regulations require that tail lamps meet certain size and visibility requirements. Clearance/marker lights can be smaller, but a 2 inch diameter taillight would not meet those requirements. There is a 4 inch diameter lamp, part # ST45RB. The lamp would typically mount in a grommet like part # A45GB set into an existing hole or using a bracket like # BK45BB.
    view full answer...
  • Wiring and Mount for Optronics 4 Inch Round Trailer Light # ST45RB
    Sealed, 4" Round Trailer Stop, Turn and Tail Light, Flush Mount, 3-Function Item # ST45RB has a plug in the back to accept pigtail # A45PB. On it the white wire is ground, black is for tail lights, and red is for brake lights and turn signals. This light can be mounted using grommet # A45GB with bracket # BK45BB. Or if mounting directly in a surface you would just need the grommet. I have linked videos of all of these parts for you.
    view full answer...
  • Replacement LED Trailer Tail Lights for a 2005 Gulfstream BT Cruiser
    Optronics trailer tail light # ST45RB is potentially a fit for your trailer if the existing lights are one of the following: Uni Bond # SE4000R Wesbar # 423541 Truck Lite # 40282R/40202R Grote # 52922 Peterson # 426R Bargman # 40-01-001 This information is likely on the light housing somewhere on your existing lights. The 2 knobs on the back are not an issue since this light would mount in a hole in the trailer or in mounting bracket # BK45BB both using grommet # A45GB. If you are not...
    view full answer...
  • Is Peterson Red Round Replacement Lens # 420-15 Interchangeable with DZ 77-845 Tail Light
    The Peterson Red Round Replacement Lens, # 420-15, is not interchangeable with the DZ 77-845 light that you referenced but I may have a solution. For just a bit more than the cost of a lens, you could replace the entire light assembly with the Sealed, 4" Round Trailer Stop, Turn and Tail Light, # ST45RB. 3-Wire Pigtail, # A45PB, and Rubber Grommet, # A45GB, would be needed in addition to the light. Unfortunately we do not offer a replacement lens that will work for your current light.
    view full answer...
  • Troubleshooting Light Not Working with the Cargo Carrier Light Kit # 52014
    If you installed the Cargo Carrier Light Kit # 52014, and all of the functions on one light are not working then it sounds like the problem is the light itself. If some of the functions worked on the light then I would say that you have a problem with the wiring somewhere. You can test the light by running a ground to the marked pin and then test the other 2 pins with a 12V power source. If you think that the wiring may be an issue then you can replace it with part # WHCETR1B. For a replacement...
    view full answer...
  • Parts Needed to Install 4-1/2 inch Diameter Light in Trailer
    Yes, all three of the parts you mentioned are what's needed to install a light assembly in a 4-1/2 inch diameter hole. The light part # ST45RB fits the # A45GB, and the pig tail part # A4PB is the correct one as well.
    view full answer...
  • Replacement Trailer Lights for Truck-Lite Products
    Part 40282R3 refers to a Truck-Lite brand round red-lens light. We have the Optronics stop/turn/tail light # ST45RB which is a direct replacement. This light uses a 3-prong plug # A45PB and can mount using grommet # A45GB. Part 50-19200Y3 refers to a Truck-Lite brand rectangular amber clearance light. As a direct replacement we have Optronics # MC65AB.
    view full answer...
  • Replacement Tail Light Recommendation for a 2006 Damon Trailer
    All I really can say is that based on the measurements a previous customer of ours submitted about the tail lights that are on their 2006 Damon trailer the closest replacement we can offer is the Miro-Flex LED Trailer Stop/Turn/Tail Light # STL23R24B. It measures 4 inches in diameter and 1-15/16 inches deep. To install this light, you would also need Rubber Grommet for 4 inch Round Trailer Tail Lights, # A45GB, and Straight 3-Wire Pigtail for Sealed Trailer Stop, Turn and Tail Lights,...
    view full answer...
  • 4 Inch Round White Trailer Backup Lights Needed for a Quick Loader Trailer
    Yes, we have the Sealed, 4 inch Round Trailer Back Up Light, # BU45CB, that has a clear lens and provides a white backup light. Along with the light you might also need a 4 inch round grommet, # A45GB, and a straight pigtail, # A45PB, or a right angle pigtail, # A47PB.
    view full answer...
  • Is the Optronics Trailer Light # ST45RB 12 or 24 Volt
    The Sealed, 4 inch Round Trailer Stop, Turn and Tail Light, part # ST45RB is designed to work with a 12 V system. I have attached a product review video for this light you can check out. This light accepts the 3-prong connector like part # A45PB. The grommet used with this light is part # A45GB and is sold separately. For a 4 inch light that is designed for a 24 volt system I recommend part # STL23R24B.
    view full answer...

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