That’s an *RGB LED swimming pool light*
*What it is:*
- *Type*: Waterproof submersible pool light. The blue rubber gasket + stainless steel rim are standard for sealing it against water
- *Lens*: The textured clear face spreads the light. Inside you’ve got a grid of LEDs
- *Use*: Mounts into the side wall of a swimming pool, fish pond, or large aquarium. Gives underwater lighting and usually has color-changing modes
- *Power*: Most of these run on 12V AC/DC for safety underwater