1. Trailer Lights
  2. Optronics
  3. Tail Lights
  4. Round
  5. LED Light
  6. Red
Optronics LED Trailer Tail Light - Stop, Tail, Turn - Submersible - 21 Diodes - Round - Red Lens

Optronics LED Trailer Tail Light - Stop, Tail, Turn - Submersible - 21 Diodes - Round - Red Lens

Item # STL55RB
lowest price pledge
Our Price: $16.23
You Save: 16%
Trailer Lights
Orders above $99 qualify for Free Shipping
Shipping Weight: 0.25 lbs
In Stock, Ships Today
zoom in icon
zoom out icon
Comment field cannot be left empty.
Name field cannot be left empty.

Thank you! Your comment has been submitted successfully. You should be able to view your question/comment here within a few days.

Error submitting comment. Please try again momentarily.

Product Images

In Use/Installed

4-5/16" Diameter round. 3-Function, waterproof LED light acts as a brake, tail, and turn signal. Durable polycarbonate housing and lens. Recessed mount with grommet (sold separately). Accepts standard 3-prong plug. Lowest Prices for the best trailer lights from Optronics. Optronics LED Trailer Tail Light - Stop, Tail, Turn - Submersible - 21 Diodes - Round - Red Lens part number STL55RB can be ordered online at etrailer.com or call 800-298-8924 for expert service.
  • All Info
  • Reviews (33)
  • Q & A (11)
  • Videos (2)
  • Photos
  • Why etrailer?

Optronics Trailer Lights - STL55RB

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

4-5/16" Diameter round. 3-Function, waterproof LED light acts as a brake, tail, and turn signal. Durable polycarbonate housing and lens. Recessed mount with grommet (sold separately). Accepts standard 3-prong plug.


  • Round LED trailer tail light serves 3 functions
    • Stop light
    • Tail light
    • Turn signal light
  • Sonically sealed, waterproof housing and lens unit is submersible
  • LEDs make great replacements for incandescent lights
    • Last 50 times longer
    • More efficient - provide brighter light with less power output
    • No bulbs to replace - no brittle filaments
  • Durable polycarbonate lens and housing
  • Red lens over clear LEDs
  • Compatible with 12V DC systems
  • Recessed mount with grommet (A45GB - sold separately)
    • Mounts in any 360 degree position
  • Accepts industry standard 3-prong plug


  • Dimensions: 4-5/16" diameter x 1-1/2" deep
  • Diodes: 21
  • Power draw at 12.8V:
    • Stop/turn: 0.208 amps
    • Tail: 0.013 amps
  • Lifetime warranty on LEDs

Optronics STL55 Series High Count LED Tail Light Dimensions

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.

STL55RB Optronics High Count LED Combination Trailer Tail Light - Stop, Tail, Turn - Submersible - 21 Diodes - Round - Red Lens

Alternate part number: STL-55RB

California residents: click here

Video of Optronics LED Trailer Tail Light - Stop, Tail, Turn - Submersible - 21 Diodes - Round - Red Lens

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

Video Transcript for Optronics LED Stop/Turn/Tail Light Installation

(Music) Today in our Equipment Trailer, we're going to be installing the Optronics sealed, four-inch, round, LED stop, turn, and tail light with 21 diodes, in the red color, part number STL55RB. Now here in our Equipment Trailer, we already have the incandescent light that's been installed in this trailer. Now while our light still does work, we are going to go ahead and change it out to the new LED style bulb, which is much brighter, as well as, gives you a much longer service life. For comparison, before we remove the old one, we're going to go ahead and turn off the light, and then turn on the running light in the brake and turn signal, so that you can see just how bright the incandescent style bulb is. Now here's what our running light circuit looks like. Next we'll go ahead and show you the blinker. Finally the break. Here's what our new Optronics light look like. Notice that there is 21 little diodes.

It is also a three-prong style design. Now in our case, we're going to be reusing the rubber grommet as well as the pigtail, but if you needed a new rubber grommet, or a new pigtail to connect to the back side of the light, I'll just go ahead and give those part numbers, as well. If you're ready to doing a new installation, or your rubber grommet is in bad shape and needs to be replaced, that part number is A45GB, and that's for a four-inch rubber grommet for round trailer lights. Now for think wiring, there's two different options. Both of them are three-wire pigtails, one of them is a right angel design, and that's part number A47PB with the wires and the plug are in the right angle. And they also make a straight wthree0wire design, that's part number A45PB. Now we'll go ahead and remove the old tail light. Simply just take small flat-head screwdriver, and work in along the edge. Go ahead and slide the old light out.

Unplug the wiring harness. Now that's a good idea why you have think light out, go ahead and remove the rubber grommet, and clean out the dirt and debris that may have accumulate there over time. Just take a paper towel and wipe everything out. You can also go ahead and wipe off the pigtail. Clean any dirt that maybe on the connection points.

Then go ahead and reinstall the grommet. Slides into place. There's a little lip here. It's what catches on the metal. Now you notice here, the existing pigtail on this trailer is the straight design. It's not the 90-degree of the angled design one.

Just to give you an idea what that would look like. This one's pretty similar to the part number I gave you. We'll go ahead and take the connector, we'll need to plug it into the back side of the light. Now it's plugged in, and we're ready to reinstall it into the rubber grommet. Go ahead and take our wires and get it work back in to the area here. Then work the tail light into the rubber grommet. Like that. Now we're ready to test it out and make sure that everything is working just fine. Now we're ready to go ahead and test out our light. We'll begin with the running light circuit. See here. Everything is working just fine. Go ahead then with the blinker or the turn signal. Finally, we'll test out the break. You can see here everything's working just fine. That will do it for the installation of the Optronics sealed, four-inch, round, LED, stop, turn, and tail light in a 21-diode design and in the red color, part number STL55RB as installed on our Equipment Trailer. (Music).

Customer Reviews

Optronics LED Trailer Tail Light - Stop, Tail, Turn - Submersible - 21 Diodes - Round - Red Lens - STL55RB

Average Customer Rating:  4.9 out of 5 stars   (33 Customer Reviews)

4-5/16" Diameter round. 3-Function, waterproof LED light acts as a brake, tail, and turn signal. Durable polycarbonate housing and lens. Recessed mount with grommet (sold separately). Accepts standard 3-prong plug.


Very nice light and great price. Excellent customer service and fast shipping 605647


All around good experience! Person I dealt with was very knowledgeable about their products and order was received as expected. 556738


Quality LED lights with pigtails! Fit great and works well. 552436


Product worked great. and service by E-Trailer was very attentive. Thanks. 604560


The lights are bright and easily seen. A wiring harness is not included and I had to order independently. Also, no screw to secure the ground wire. I was able to adapt these lights to an old trailer with different trailer light housings fairly easy. 571840


I am very pleased with product and extremely satisfied with prompt service and shipping and I will definitely buy from e trailer in future Thanks 733367


Very nice customer services ! Great pro ducts! 718499


Great customer service. I would definitely shop here again and recommend them anytime. I got exactly what I need at a great price and it shipped right away. Thank you! 694089


they work great, no issues 682715


This light fit into my new used truck camper like a pro. etrailer.com has all my future business of this sorts. The product was accurately described and the website is as easy to navigate as any I can think of. 611036


Good quality and value. Quick free shi pping. 583331


good product, looks nice lit and easy to install, oredered on Sunday received on Friday. Took me approx. 1 hour to install all 15 lights on my dump trailer. 504799


Great Product & Service! 457399


These are fantastic. I really like the brightness, how they install (quick connector plug) and the fact that they are sealed. They mount in gasket that also provides shock protection and a good tight fitting. Had no issues with either one to date. Would buy these for all future trailers. Looks great, works great. 455182


Love the lights. Appear well made and a big improvement in intensity over the old ones they replaced. 437607


Great lighting power in these lamps. 431186


Nice lights well built very solid construction will buy again 404535


Correct light to replace my trailer lights. Great product 400934


A+++ 399468


Fit perfectly and give more light than the ones I replaced. etrailer wins again! 370204


The product arrived quickly and was just as described. My trailer is older and I was having trouble finding replacements for the tail lights. Their sales rep, Cathy T., was knowledgeable and friendly. The next time I need parts for my horse trailer, I will go directly to etrailer. 337837


Excellent service and very bright light s. 332121


Fit perfect easy to install replaced 20 year old trailer lights LED. BIG Difference! 329011


We replaced all 4 tail lights on our 5th wheel trailer with LED lights. They were easy to replace and work great. 326048


received the lights in perfect condition and extremely quick. they are perfect for my new tail lights which will be mounted to a piston for my rat rad truck. 314423

mike p - 11/07/2017

Show More Reviews

Ask the Experts about this Optronics Trailer Lights

  • Replacement Tail Light For Forest River Georgetown XL RV
    I'd be happy to assist you. It sounds like you need the Sealed, Flush Mount Tall Rectangle LED Trailer Stop, Turn and Tail Light, Grommet and Plug, 12 Diode # STL34RB but most of the pictures I see have round tail lights like the Sealed, 4" Round, LED Stop/Turn/Tail light, 21 Diode - Red # STL55RB. If this is not the correct part, then send me a photo with the measurements of the light and we will get you what you need. The numbers and letters that are actually printed on the light...
    view full answer...
  • Recommended Trailer Tail Lights for 4.25 Inch Opening
    The LED Trailer Tail Light # STL42RMB has screw mounting holes that are 4-1/4 inches on center. The smallest hole this light will fit is 4 inches. You will have difficulty mounting this light as your opening matches the mounting hole locations so you won't get proper hold. You may want to use the Rubber Grommet for 4" Round Trailer Tail Lights # A45GB along with the # STL55RB which won't use any screws to mount. You will also want the 3 wire pigtail # A45PB.
    view full answer...
  • Recommended LED Replacement Lights for 2005 Damon Daybreak Motorhome with Load Resistors
    The Sealed, 4" Round, LED Stop/Turn/Tail light, 21 Diode - Red # STL55RB will work great on your motorhome. You will simply need to use the wiring pigtail # A47PB for each light. You will simply need the butt connectors # DW05744-5. On some vehicles, when switching to LED lights, there is a load resistor needed to prevent hyperflashing but this is not always needed. If you do end up needing a load resistor, I recommend the Putco LED Light Bulb Load-Resistors - Aluminum - Qty 2 #...
    view full answer...
  • Replacement Tail Light for 2009 Ranger Boat Trailer
    Sometimes it is possible to replace a broken trailer light with one that uses a different type of installation but since we offer a very wide range of lights you may very well be able to find an exact OEM-style replacement. It sounds like you have a light like # STL42RB which has a 3-hole mounting flange. I linked our main page for trailer tail lights of all shapes and sizes. On the page you can simply click on the filters for light shape, light type (LED or standard bulb), lens color,...
    view full answer...
  • Replacement 4 Inch Reverse Lights to Replace Truck Lite Stop Turn Lights
    If the cut out diameter of your vehicle is 4-1/2 inches then you can install the part # STL55RB in place of what you have with the grommet part # A45GB. For a similar clear version of this light you would want the # BUL43CB.
    view full answer...
  • 4 Inch Round Trailer Tail Light Cutout Size
    The closest to 4 inch round lights we have is the Optronics LED Trailer Utility Light # BUL43CB or Trailer tail Light # STL55RB which are actually 4-5/16" diameter x 1-15/16" thick. These are designed to fit the Rubber Grommet for 4" Round Trailer Lights - PVC # A45GB which requires a 4-1/2 inch diameter cutout. You will also need wiring pigtail # A47PB. If you are interested in the Optronics Trailer Tail Light - Stop, Turn, Tail - Incandescent - Round - Red Lens # ST40RB you asked...
    view full answer...
  • Recommended Grommet for Optronics 4 Inch Round LED Light # STL55RB
    Both the Rubber Grommet # A45GB and the Notched Rubber Grommet # A45GNB that you referenced will fit and work well with the Optronics 4" Round LED Light # STL55RB. The only difference between the two grommets, as you mentioned, is the notched cut out in the lower portion of the unit. This is not necessary for wiring or fitment, but it will allow for a bit of an easier install.
    view full answer...
  • Mounting of Optronics 4 Inch Round Tail Light
    The Optronics Tail Light # STL43RBX does not need a bracket for mounting. It has a built in flange and includes a rubber grommet. A similar light, # STL55RB, uses a stainless steel mounting flange # A45SB. Both lights can be connected using a 3-wire pigtail, # A45PB, or # A47PB for a right angle.
    view full answer...
  • Replacement 4 Inch Round Tail Lights With Stop/Turn/Tail Functions
    We have many 4 inch round tail light options like the Peterson Round Trailer Tail Light, 2 Stud Mounting, Right Hand # 431800. We also have LED options like Optronics Sealed, 4" Round, LED Stop/Turn/Tail light, 21 Diode - Red # STL55RB. I've linked the page to our 4 inch round tail light options for you that have the stop/turn/tail functions.
    view full answer...
  • Bright LED Trailer Taillight Recommendation for Replacing 4 inch Trailer Light
    The Optronics LED Trailer Tail Light # STL55RB is going to the brightest option we have and will work great for your application. Each of these has 21 diodes in it which means it will put out quite a bit of light. The people behind you will have no problem seeing them! You'll also need the grommet part # A45GB to install the light as well as the pigtail part # A45PB. The mentioned light does not have reflectors but is very bright, the next brightest option that does have reflectors...
    view full answer...
  • 2 inch and 4 inch Diameter Recess Mount LED Clearance Light Recommedation
    For the 2 inch light you would want the part # MCL55RB with the grommet part # A54GB and pigtail part # A46PB. For 4 inch we have the part # STL55RB. You would need the grommet part # A45GB and the same pigtail # A54GB. I wish we had a 3 inch option, but you may be able to enlarge the 3 inch holes to match the 4 inch ones.
    view full answer...

Do you have a question about this Trailer Light?

  • Why etrailer.com?

    At etrailer.com we guarantee:
  • Highest quality trailer lights for the best price.

    Our Lowest Price Pledge ensures you will never overpay for the parts you need.
  • Real product know-how.

    We make sure that the products we sell are what we say they are, and that they work the way they are supposed to work. Get real advice from a real person who has the knowledge and expertise needed to solve your problem.
  • Most detailed, accurate trailer light information available.

    Because we take providing accurate product information seriously, we take our own detailed product photos, demo videos and installation videos, as well as verify measurements, instructions, and vehicle fit information.
  • Installations, made easy.

    We love helping people and have the most highly-trained customer service, hands-on experience, step by step videos and installation instructions.
  • Fast shipping.

    Your order is automatically routed to get out of our warehouse and to your door as quickly as possible. Receive free shipping on orders over $99.
  • Personalized service for life.

    We provide one-on-one, personalized service from the ordering process through the life of your product.
  • Trusted since 1946.

    We've been serving customers since our parts store first opened in 1946 and continue to be recognized by our customers, our vendors and third parties for exceptional service.
  • Returns Policy

    Need to return an item? No problem. Please read our Returns Policy for more information.

Info for this part was:

Written by:
Tyler C
Expert Research:
Jameson C
Expert Research:
Adam R
Updated by:
Adele M
Updated by:
Jenny M
Updated by:
Brian T

At etrailer.com we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time. Let us know if anything is missing or if you have any questions.

Product Experts Available Now!

Call 800-298-8924