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Trailer Clearance or Side Marker Light w/ Reflector - Incandescent Amber Lens -.156 Female Barrels
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Optronics

Trailer Clearance or Side Marker Light w/ Reflector - Incandescent Amber Lens -.156 Female Barrels

Part Number: OPT37WR
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$3.70
Retail:$5.69
You Save: 35%
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etrailer Installation
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4" x 2-1/16". Incandescent trailer light serves as a clearance or side marker light when properly mounted. Built-in reflector. Surface mount to trailer - hardware not included. 2-Wire design with 0.156 female barrels. P2 rated. Great Prices for the best trailer lights from Optronics. Trailer Clearance or Side Marker Light w/ Reflector - Incandescent Amber Lens -.156 Female Barrels part number OPT37WR can be ordered online at etrailer.com or call 1-800-940-8924 for expert service.
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  • Videos (1)
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Optronics Trailer Lights - OPT37WR

Highlights

  • One Light, Two Uses: Works as a clearance or side marker light when properly mounted.
  • No Extra Reflector Needed: Built-in reflex reflector meets visibility needs in one unit.
  • Simple Hookup: 2-wire design with 0.156" female barrels connects easily to 12V DC.
  • Durable Build: Black ABS housing and amber acrylic lens handle everyday trailer use.
  • Low Power Draw: Uses 0.2 amps at 12.8V for efficient incandescent lighting.
  • Sized to Fit: 4" Lx2-1/16" Hx1-3/32" D with 3" center-to-center mounting holes.

Features to know about

Better Night Visibility and Compliance: P2-Rated Incandescent Clearance Light

This light delivers solid illumination where you need it most. With its P2 rating, it produces a 45-degree beam to either side of center for a total of 90 degrees of coverage—bright enough to serve as a clearance or side marker light when properly mounted. It meets DOT requirements, so you can count on it for dependable performance that keeps your trailer visible and compliant in low-light conditions.

No Extra Reflector Needed: Built-In Reflex Reflector

A built-in reflex reflector means one less step during install. It removes the need for a separate reflector, keeping your setup clean and functional. Whether you’re upgrading or replacing old lights, this all-in-one design saves space while still giving you the visibility and reflection required by lighting regulations.

Simple Wiring and Mounting: 2-Wire Design with .156" Female Barrels

Wiring is straightforward thanks to the 2-wire setup with .156" female barrels. Hard wire it to your 12V DC system, and you’re ready to go. The light surface mounts directly to your trailer using standard hardware (not included), with 3" center-to-center spacing between mounting holes. It’s a simple, solid fit that’s easy to maintain.

Durable and Serviceable Construction: Replaceable 194 Bulb and Sealed Housing

Built with a black ABS housing and an amber acrylic snap-on lens, this light holds up well against road wear. The replaceable 194 bulb keeps maintenance easy—no sealed unit to toss when the filament goes out. At 4" long by 2-1/16" tall and 1-3/32" deep, it’s compact but tough, ready for steady use without taking up extra space.

Reliable Power Performance: Low Draw and Long Warranty

Drawing just 0.2 amps at 12.8 volts, this incandescent light runs efficiently on standard trailer circuits. It’s built for dependable service and backed by a 3-year warranty for peace of mind over the long haul.

Specs

Dimensions

  • Dimensions: 4" long x 2-1/16" tall x 1-3/32" deep
  • Distance between mounting holes (center on center): 3"
  • Dimensions (W x H x D): 4.000 x 2.063 x 1.094

Dimensional diagram of Optronics MC31 Series amber trailer clearance and side marker light showing 4 inch by 2-1/16 inch size and oblong shape.

Electrical

  • Voltage: 12V DC
  • Power draw at 12.8 volts: 0.2 amps
  • Amp Draw: 0.2A
  • Bulb type: 194
  • Connection: Hard wired, .156 female barrel(s)
  • Wire Design: 2-Wire design with 0.156 female barrels

Rating and Compliance

  • FMVSS: P2 A
  • DOT compliant: Yes
  • P2 rated: Yes

Construction

  • Housing Material: ABS
  • Lens Material: Acrylic
  • Lens Color: Amber
  • Mount: Surface
  • Size/Shape: Oblong
  • Weight: 0.088 lbs.

Warranty

  • Warranty: 3-Year warranty / Three Year Warranty

MC31A15B2 Optronics Trailer Clearance or Side Marker Light w/ Reflex Reflector - Incandescent - Oblong - Yellow Lens - P2 Rated - 0.156 Female Barrels





Video of Trailer Clearance or Side Marker Light w/ Reflector - Incandescent Amber Lens -.156 Female Barrels
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Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.




Video Transcript for The Low-Down on the Trailer Clearance or Side Marker Light w/ Reflector

Hi there. I'm Michael with etrailer.com. Today, we're gonna take a quick look at this incandescent amber trailer clearance or side marker light. This is a D.O.T compliant four inch long by two and approximately two and one sixteenth of an inch tall and about one and three, thirty seconds of an inch deep incandescent trailer light. And that is going to serve as either a clearance light or a side marker light depending on how you have it mounted. So this is P2 rated, which means that it will produce a 45 degree angle of light to either side of the center line for a total of 90 degrees of coverage.

This beam pattern can be seen straight on but it is harder to see from the side. So it can be used either as a side marker light or as a clearance light but it cannot function as both simultaneously. Now this is gonna have a built in reflector that is going to remove the need for a separate reflector. The amber snap on acrylic lens does cover your incandescent bulb. That is an incandescent 1 94 bulb inside there.

So it is gonna be very easy to replace. Just pop off the lens, pull out the current bulb put in the new one. Anytime you need to replace it on the back we do have this durable A.B.S plastic housing. It is gonna be a surface mount installation. The hardware to get it mounted is not included.

Again, just pop off the lens. You'll put your hardware through the distance between our mounting holes here. It's right at three inches center to center. This is going to have a two wire design with the .156 female barrels. It is gonna be compatible with your 12 volt DC systems.

It's only gonna draw about 0.2 amps on your 12.8 volt system. So if you are looking to replace either your trailer clearance or your amber side marker light this is gonna do a great job for you. That completes our look for today and again on Michael with etrailer.com. Thanks for watching..

Customer Satisfaction Score:

Ratings & Reviews

4.9

4183 reviews
5 Stars
(3740)
4 Stars
(339)
3 Stars
(56)
2 Stars
(19)
1 Star
(29)
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by:
Perfect fit, bright, easy hookup. I kinda bumped a tree and took out the ones on my trailer. These work!
by:
Part worked great! Fast shipping
by:
Great replacement for the originals! Very nice and bright!
by:
Great price,quick service,what's not to like.Will be using again.
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Bought to replace an obsolete broken clearance light on my 10 year old class A motorhome with new lights. I did add heavy duty LED 194 bulbs that really brightened them up. Great value!
Christopher H. profile picture
Etrailer Expert

Christopher H.

10/1/2026

Glad this worked well for you Al! Appreciate you including the photo.

by:
Exact fit! Looks just like the one that was recently damaged. The lens was the only thing broken on the old light so I screwed the new one on in less than a minute and now I have a replacement ready when/if needed. Not extra holes to drill.
by:
The Trailer Marker Lights were an exact replacement. etrailer has always provided the best service. Have purchased from etrailer several times over the years. Will continue to purchase from etrailer.
by:
Exact replacement for the original marker lights on my trailer. Well packaged and arrived in great condition. Simple to install.
by:
excellent product and easy replacement for existing failed side light.
by:
Exact replacement part I needed.
Louis profile picture

Louis

8/30/2026

Great

Jerred H. profile picture
Etrailer Expert

Jerred H.

8/30/2026

@Louis Happy to hear that!
by:
Easy ordering, great follow up, excellent communication. Will order through etrailer again. Thanks for the fast delivery.
by:
This side marker light was an exact replacement for a busted light on my boat trailer.
by:
The lights worked great and were of good quality. The covers fit firmly in place and I won't have to worry about them coming off like the old lights did.
by:
Absolutely perfect replacement for broken Trailer light!
by:
These were a match to my Grand Design lights. I need to replace cracked covers. Fit perfect.
by:
Exact replacement, just wanted the lens, now have a spare body and bulb. Fast & economic shipping
by:
It's very hard to find a black base on marker lights in local stores throughout the US. I'm glad etrailer carries black base marker lights to match my camper's other lights. This worked great!
Susan profile picture

Susan

11/11/2025

This marker light is still working. I have no complaints.

by:
Arrived quickly and is a fair price; plus it's a direct replacement for the old one, no additional holes to drill.
by:
Prompt delivery. The side marker light could have had a longer power wire for my application. But not a show stopper.
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Info for this part was:

Employee Lindsey S
Written by:
Lindsey S
Employee Wilson B
Updated by:
Wilson B
Employee Manda E
Updated by:
Manda E
Employee Carrie F
Updated by:
Carrie F
Employee Michael B
Installed by:
Michael B

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