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Swapping out old bulbs for LEDs is a big upgrade, and this 4" x 1" rectangular light makes it easy. It uses six red LEDs under a polycarbonate lens to put out a bright, even glow while drawing only 0.057 amps at 12.8V. That means it’s energy-efficient, long-lasting, and doesn’t need bulb changes or worry about filaments breaking. It’s built to run cool and steady so you can count on consistent light every time you hook up power.
Moisture ruins lights fast, but this one’s ready for the water. The housing and lens are sonically sealed into a single waterproof unit that won’t let water inside even when fully submerged. It’s ideal for wet roads or launching at the boat ramp—no corrosion, no moisture damage, just clear reliable light each time you use it.
This light mounts flat and secure wherever you need it. The surface-mount design has a 3" center-to-center hole spacing, so installation is straightforward with the right screws for your surface material. The 2-wire hookup—power lead and ground wire—makes wiring fast and clean without extra adapters or plugs to chase down.
Built with a P2 rating, this light projects a 45-degree beam on either side of centerline for a total of 90 degrees of coverage—perfect for use as either a clearance light or a side marker when mounted properly. It meets DOT standards too, so it provides the right output and visibility you need for safe operation day or night.
Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.
Here we have Optronics thin-line LED trailer clearance and side marker light, part number MCL66RB. The lens of this light is sealed and waterproofed with the housing. Inside are six LEDs that draw a total of 0.048 amps at 12.8 volts. The light is designed to surface mount using mounting holes that are 3 inches on center. The light is a two wire design, meaning you will have one wire lead for ground and the other wire lead will serve as your power connection. Next we are going to hook up the light to a power supply so you can see how it looks. We will connect the white wire to our ground and the black wire to our power. Next we will turn off the overhead lights so you can see how bright the light is. And that does it for Optronics thin-line LED trailer clearance and side marker light, part number MCL66RB.
Customer Satisfaction Score:
100% were satisfied with this product
0% of customers were not satisfied
Ratings & Reviews
Great product
Product arrived quickly and in good condition. Lights are easy to install and very bright.
Excellent lamp, easy to use.
As advertised. Lights were delivered promptly and free of any damage.
Great transaction!
Perfect fit, no problem to install, great price!
Exact Replacement
Great seller. Great lights. Easy install. seller followed the deal to my complete satisfaction. I will use again.
Teresa was very helpful in changing my order quickly and product was received timely,, Thanks Ron
Fast and efficient, we have our boat trailer back in service in just few days. Thank you, and will definitely refer your site and will order again.
Great visibility better than the OEM that came on my travel trailer. Love-em.
Simple and smooth design, two screws and two connectors to install.
Tip notch product and customer service. Probably the best I've experienced. I got 11 of these lights and they are obviously well made. Will definitely shop around.
Just as listed.
Works perfectly
Excellent lights and I looked all over the net to find these particular lights and Etrailer.com had exactly what I needed and great price and fast shipping!! Will buy from this website again....
It would be difficult , if not impossible, to have a more helpful person facilitating the placing of an order than Paula at etrailer. I swapped out all incandescent light fixtures on my trailer with led, and the buyiing/ selection process was made a pleasure with her help.
These are nice, they are completely sealed from moisture and are more than bright enough. Extra work to change the entire fixture instead of a light bulb but more than worth it.
Replace original equipment same light excellent easy installation
Super Bright, cant wait to use under water !!
Put these LED lights on the side of my trailer,looks great and vibrant,and there totally sealed,no maintenance .
Jim L.
5/26/2016
Product great, e trailer had what I needed
Nice bright marker light and easy to connect to existing wire harness.
David D.
4/3/2018
The 2 amber and 2 red lights I purchased are still working just fine. Great lights and I would buy them again.
Great product and service was excellent
Replaced exactly what I needed
Fit perfectly where the old lights were. Perfect replacement.
Brooke M.
4/14/2025
Too "light-git" to quit! [gotta say it with a sort of Australian accent for it to work]
I bought 2 of these lights.They work great and are exactly what I needed. Customer service was great and was quick to clear up receiving the wrong light for one of them. I will use them for future purchases if needed.
Craig
11/5/2025
Still working great. No problems.
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C. C.
11/26/2015
Just fine. Great intensity and reliability.