bing tracking image
  1. Trailer Lights
  2. Peterson
  3. Tail Lights
  4. Oval
  5. Incandescent Light
  6. Red
Peterson Trailer Tail Light - Submersible - Stop, Tail, Turn - Incandescent - Oval - Red Lens
Peterson

Peterson Trailer Tail Light - Submersible - Stop, Tail, Turn - Incandescent - Oval - Red Lens

Part Number: M421R
In Stock
$14.40
Retail:$25.26
You Save: 43%
Trailer Lights
zoom in icon
slider vertical icon
zoom out icon
Comment field cannot be left empty.
Name field cannot be left empty.
By submitting this form, you understand and agree to our Terms of Sale, Website Terms of Use and Privacy Policy.

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

6-1/2" x 2-1/4" Oval. Waterproof, incandescent trailer light functions as a stop, tail, and turn signal light. Recessed mount with grommet (sold separately). Accepts 3-prong plug. Great Prices for the best trailer lights from Peterson. Peterson Trailer Tail Light - Submersible - Stop, Tail, Turn - Incandescent - Oval - Red Lens part number M421R can be ordered online at etrailer.com or call 1-800-940-8924 for expert service.
  • All Info
  • Reviews (1225)
  • Q & A (0)
  • Photos

Peterson Trailer Lights - M421R

Highlights

  • One Light, 3 Functions: Provides stop, tail, and turn signals for clear communication on the road.
  • Reliable In Wet Conditions: Sealed, waterproof housing keeps moisture out for lasting performance.
  • Simple Plug Connection: Accepts industry-standard 3-prong PL-3 plug for quick setup.
  • Secure Fit: Recessed mount with grommet (sold separately) keeps the light protected and stable.
  • Durable Build: Polycarbonate housing and red lens stand up to road and weather wear.
  • Road Legal: DOT compliant so your trailer lighting meets safety regulations.
Made in USA

Features to know about

Reliable Visibility with a Classic Glow: 6-1/2" x 2-1/4" Incandescent Tail Light

This oval trailer light keeps things simple and dependable. At 6-1/2" long, 2-1/4" tall, and 2-3/8" deep, it delivers bright stop, tail, and turn signals through a red lens over an incandescent bulb. Running on 12V DC and drawing 2.1 amps at 12.8V, it gives off that familiar incandescent brightness that’s easy to see in traffic or at night. DOT compliance means you can count on it to meet safety standards wherever you tow.

Dealing with Wet Conditions: Sealed and Submersible Construction

Water and wiring don’t mix, but this light is built to handle it. The sealed housing and lens unit are waterproof and submersible, keeping moisture out even when your trailer is backed into the water. That sealed design protects the bulb and internal components from corrosion so the light keeps working trip after trip, whether you’re rinsing off road dust or launching at the ramp.

Clean and Simple Wiring: Industry-Standard PL-3 Plug Connection

Hookup couldn’t be easier thanks to the standard 3-prong PL-3 connection. It plugs right into matching trailer wiring without splicing or guessing which wire goes where—just plug in and go. That standard connector also makes future replacements or swaps straightforward since it fits widely used harnesses like part #431-491 or #421-491 (sold separately).

Close-up photo of a standard PL-3 three-prong plug used for connecting the Peterson M421R trailer tail light, showing the wiring configuration.

Neat Installation Every Time: Recessed Mount Design

The recessed mount keeps the light tucked in close for a clean look and added protection. It installs with a grommet (sold separately) that cushions the housing and gives the setup a finished edge. If you’re replacing an old light, you can often use the existing hole; if you’re starting fresh, cut a new opening or use a mounting bracket to complete the job. The result is a solid, professional-looking fit that stays put mile after mile.

Specs

Dimensions

  • Overall dimensions: 6-1/2" long x 2-1/4" tall x 2-3/8" deep

Diagram showing the dimensions of the Peterson M421R oval red trailer tail light, highlighting its 6-1/2-inch length, 2-1/4-inch height, and 2-3/8-inch depth for recessed mounting.

Electrical

  • Bulb type: incandescent
  • Power draw at 12.8V: 2.1 amps

Warranty

  • Warranty: 1-Year limited warranty

M421R Peterson Trailer Tail Light - Submersible - Stop, Tail, Turn - Incandescent - Oval - Grommet Mount - Red Lens





Customer Satisfaction Score:

Ratings & Reviews

4.8

1224 reviews
Review sort icon
6-1/2" x 2-1/4" Oval. Waterproof, incandescent trailer light functions as a stop, tail, and turn signal light. Recessed mount with grommet (sold separately). Accepts 3-prong plug.

by:

Great seller



by:

exactly what I needed, purchased easily and delivered quickly!



by:

Matches the original exactly.



by:



by:



by:

Great service



by:

Expedient



by:

great co. good prices



by:

Product came when it was supposed to. Price was ok. Found out I could have bought it $3 cheaper locally.



by:

Scuffed up surface from no packaging and thrown in a box to rattle around with other items in the shipment. No biggie, it's just a trailer. I got the scuffs off with plastic polish.



by:

Perfect.



by:

Love etrailer



by:

I ordered seven front lights seven rear lights and7 tail lights and a tag light. All of them were thrown in the box and we’re scratch on shipping. None of it was Wrapped 1

Sierra K. profile picture

Sierra K.

9/22/2021

Sorry to hear about this. Customer Service will reach out to you.



by:

I love etrailer



by:

I think this is a good product and I was able to get exactly what I needed the first time. No problems.

William profile picture

William

9/10/2024

Great product. Works great and is easy to install



by:

I was surprised that I was able to get the part so easy. It is good to know where to get trailer parts



by:

Great product. Great price and fast shipping. Purchased to replace one that had gone out. Direct replacement made it an easy and quick repair.



by:

Direct replacement for the factory installed brake/turn signal/tail light on my 20+ year old trailer - I was really worried about finding the correct replacement parts but etrailer.com had everything I needed. The ordering process was a breeze and my order arrived quickly



by:

Appreciate the timely shipping. Products were the exact match for what I needed. Unfortunately one of the trailer wire connectors was damaged so now I need the 3 wire plug connector.



by:

Quick ship and perfect fit!



by:

Haven't installed yet but received in a timely manner. strailer is a great source for parts.



by:

Never had a problem with items I bougth from eTrailer over the past decade



by:

Great service. User fr



by:

Exactly what I ordered and needed. Great light.

Don profile picture

Don

4/3/2026

Lights were of great quality. Still on my trailer and working just great

Heather A. profile picture
Etrailer Expert

Heather A.

4/3/2026

@Don Hey Don, really appreciate you coming back with the one year update. That’s great to hear they’re still working just as well, especially with something like trailer lights where you really just want them to be reliable every time you hook up. Sounds like they’ve held up exactly the way they should. Are you still running the same trailer setup, or have you made any changes since you installed them?


by:

Exactly the replacement I needed for my 2002 trailer, glad it was so easily available.


25
25

See what our Experts say about this Peterson Trailer Lights

  • Dimensions of the Petersen Trailer Tail Light
    Hey Michael, the Petersen Trailer Tail Light # M421R measures 6 1/2" wide, 2 1/4" tall, and 2 3/8" deep. I have attached a diagram for you to check out as well :) If you need anything else, please feel free to drop a comment and let me know!
    view full answer...
  • Replacement Tail Lights and License Plate Light for a Triton PWC LTWC1 Trailer
    We sure do Brad! To replace a rear tail light on your Triton PWC LTWC1 trailer, I recommend the Peterson LumenX LED Trailer Tail Light item # PET32NV. This is the LED upgraded version of the item # M421R that came stock on your trailer. The Peterson LumenX LED Trailer Tail Light item # PET32NV has identical dimensions. However, it is going to be much brighter and last longer. For the slight increase in cost compared to an incandescent replacement, I strongly suggest this upgrade. It does...
    view full answer...
  • Replacement Light for a Peterson Manufacturing 421H 6.5" Oval Trailer Tail Light
    Hey Hunter. From what I could find online the Peterson 421h is a 6.5" oval, surface-mount stop, turn, and tail light. To replace it, I recommend the Peterson LumenX LED Trailer Light item # M821R-10. This submersible LED light measures 6-1/2" long x 2-1/4" tall x 1-7/16" thick. It uses a PL-3 connector that works with the 3-prong plug item # 421-491. The Peterson LumenX item # M821R-10 provides brake, tail, and turn signal functions. It is sold individually. It has 10 built in diodes that...
    view full answer...
  • Optronics LED GloLight Replacement for Peterson M421R Grommet Mount Trailer Tailllight
    The Peterson 421R which we carry as part # M421R is a grommet mount 3 function taillight. Optronics does indeed offer an LED GloLight that would work as a replacement, which is available as part # STL111RB. You'll also need the wiring pigtail, part # A45PB. If you need the mounting grommet, they're available as part # A70GB. You can see a product video for the # STL111RB GloLight by using the provided link.
    view full answer...
  • Does Power Need to Be Removed From Submersible Light Before Backing Into Water
    To replace your Peterson M421R light you'll need the Peterson Trailer Tail Light # M421R. This installs with a simple plug in the back so the installation itself should be pretty easy to do. Just be sure to unplug your trailer wiring prior to backing into the water next time. The submersible rating on the light means the light won't be ruined if it touches water, but you still need to disconnect the power since water can short circuit the light.
    view full answer...
  • Is Etrailer Logo Removable from Peterson Trailer Lights
    The etrailer logo is a sticker placed on the Peterson Clearance lights # M146R for photo and video use. This line of lights including # M142R and # M421R does not come with the sticker. If you do by chance receive a product with this sticker it is easily removable.
    view full answer...

Do you have a question about this Trailer Light?


Info for this part was:

Employee Jacob T
Video Edited:
Jacob T
Employee Kathleen M
Installed by:
Kathleen M
Employee Aidan B
Installed by:
Aidan B
Employee Daron K
Edited by:
Daron K
Employee Brian T
Written by:
Brian T
Employee John S
Video by:
John S

At etrailer 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 1-800-940-8924