Review on Ultra-Thin Dimmable Dome Recessed Ceiling Lighting - KITASST 12V LED RV Lights Interior Fixture for RV Accessories Camper Trailer Boat Motorhome Sailboat, Waterproof, 3000K Warm White (4-Pack) by Leonard Herrera

I had no idea how small 4 inches was. Light, they have very long connecting wires, and the polarity of those wires is marked on the pre-tinned ends. They use a spring loaded metal bracket to slip through and then stay in the mounting hole. I thought the diffuser worked fine (couldn't see separate light sources). For small spaces in a DC system (van, boat, maybe even a covered trailer) these theses seem good. I don't think they are advertised as waterproof so I suspect they are not waterproof. suitable for external applications.