1. What size do you need? If you are replacing existing recessed lights, you need to purchase an LED retrofit module that matches those dimensions. If you’re unsure, just measure the diameter of your existing recessed downlights (not including the trim). Your LED retrofit module will be either four, five, or six inches in diameter.
2. Where is the installation location? If you are installing in a bathroom or any other area where moisture might accumulate, make sure to select an LED retrofit module that is “wet location approved.”