Review on DOT Certified 4-Inch LED Trailer Tail Light Kit: Red and Amber Lights with Grommets, Plugs, and IP67 Waterproof Design - Ideal for RVs and Trucks by Lance Foster

I'm quite experienced and usually approach projects fairly easily and don't lose focus and composure. The installation of these lights almost wooed me. I was so angry that I thought I had died and in some debauchery or maybe some very special and elaborate prank. It's all serious when you're done with it. DO NOT trust the 4.5" mounting cutout. I made some custom taillight housings for a bus - spent a lot of time doing prep work - all nice, neat and weatherproof - only to find I had to cut big holes. They're probably closer to 4 and 7/8. The lights are working and still in use. But if you end up with them, just take the directions and use them to set everything you're working on on fire. It seems like people who swap out lamps are easier than people who do custom work.