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Trailer Clearance or Side Marker Light w/ Reflector - Incandescent - Oblong - Red Lens
etrailer Installation
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Optronics

Trailer Clearance or Side Marker Light w/ Reflector - Incandescent - Oblong - Red Lens

Part Number: MC31RB
In Stock
$3.52
Retail:$10.29
You Save: 66%
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etrailer Installation
We'll connect you with nearby partnered installers who know this exact setup.
4" x 2-1/16". Waterproof, incandescent trailer light serves as a clearance or side marker light when properly mounted. Built-in reflex reflector. Surface mount to trailer - hardware not included. 1-Wire design. P2 rated. (1) 194 Bulb. Great Prices for the best trailer lights from Optronics. Trailer Clearance or Side Marker Light w/ Reflector - Incandescent - Oblong - Red Lens part number MC31RB can be ordered online at etrailer.com or call 1-800-940-8924 for expert service.
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Optronics Trailer Lights - MC31RB

Highlights

  • Easy Replacement Fit: Mounts on 3" centers with a simple 1-wire ground setup.
  • Two Uses in One: Works as a clearance or side marker light when properly mounted.
  • Built-In Reflector: Eliminates need for a separate reflector, keeping setup simple.
  • Long-Lasting Housing: Durable red polycarbonate lens resists road wear.
  • Low Power Draw: Uses a 194 bulb pulling only 0.2 amps at 12.8V.
  • Road Legal: P2 rated and DOT compliant for safe, visible lighting.

Features to know about

Reliable Visibility Day or Night: P2-Rated Incandescent Light

This oblong red light keeps things simple and effective. It’s P2 rated, which means it puts out a 90-degree beam pattern—45 degrees to either side of center—for clear visibility from straight on. When mounted properly, it serves as a dependable clearance or side marker light that meets DOT compliance standards. At 4" long and 2-1/16" tall, it’s compact but bright enough to make your trailer visible and safe on the road.

No Extra Reflector Needed: Built-In Reflex Reflector

Sometimes you don’t want extra parts to mount or maintain. This light solves that by including a built-in reflex reflector right in the lens. That means you get both light and reflection in one piece, keeping your setup clean while still meeting safety requirements. No need for a separate reflector plate—it’s already integrated into the housing.

Straightforward Installation: Surface Mount with Single Wire Design

Mounting this light is about as easy as it gets. The surface-mount design uses two holes spaced 3" apart, and grounding happens through the mounting hardware itself. With only one wire for power, there’s no guessing on connections. Just bolt it up, connect your wire, and you’re done. The compact size also makes it easy to fit into tight spaces without fuss.

Durable and Serviceable: Polycarbonate Housing with Replaceable 194 Bulb

Built with a tough polycarbonate housing and snap-on red lens, this light stands up to regular use without cracking or fading easily. Inside, it uses a standard 194 bulb that draws just 0.2 amps at 12.8 volts—so it’s efficient and easy to replace when needed. If you ever have to swap the bulb, it’s quick to do without replacing the whole fixture.

Dependable Construction for Everyday Use: Waterproof and Backed by Warranty

Even though it’s not meant for submersion, the waterproof construction helps keep moisture out during rain or washdowns. It’s built for consistent performance under normal towing conditions and comes backed by a 3-year warranty for added peace of mind.

Specs

Dimensions

  • Overall dimensions: 4" long x 2-1/16" tall x 1-3/32" deep
  • Distance between mounting holes (center on center): 3"

Dimensional diagram of the Optronics MC31RB red oblong trailer clearance and side marker light showing overall measurements and mounting dimensions.

Electrical

  • Bulb type: 194
  • Power draw at 12.8 volts: 0.2 amps

Warranty

  • Warranty length: 3-Year warranty

MC31R Optronics Trailer Clearance or Side Marker Light w/ Reflex Reflector - Incandescent - Oblong - Red Lens - P2 Rated

Alternate part number: MC-31R





Ratings & Reviews

4.9

4189 reviews
5 Stars
(3746)
4 Stars
(339)
3 Stars
(56)
2 Stars
(19)
1 Star
(29)
Review Sort Icon
by:
Fast delivery just want.i wanted described perfectly
by:
Good quality for the price. Delivery time was excellent.
Great service on the question I had. Will buy from etrailer again.
by:
Great marker lights for trailer up grade
by:
2003 Featherlite 3-Horse Fifth Wheel
Perfect for the job and great price!!
by:
Easy to install and work good.
by:
amazing quality for price - very happy !!!!
by:
thanks for the fast delivery they look like the will last a long time I live in the desert and everything dries out quickly thanks again art
by:
Still working
by:
2002 Fleetwood Terra Motorhome
Exactly what I ordered. Great service and received in great condition. Company was very efficient with letting me know when the order would be received.
by:
Very Good
by:
Lites arrived in a timely fashion.

Go
od quality, whish they were brighter.
by:
of what I have, but it will work in place of what I have.
by:
great
by:
All good
by:
Good products & good prices
by:
correct size
by:
by:
hassles
by:
great quality
by:
by:
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.
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Info for this part was:

Employee Michael H
Expert Research:
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Employee Laura H
Updated by:
Laura H
Employee Wilson B
Updated by:
Wilson B
Employee Brian T
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Employee Cole B
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