To install a light in your pool or spa, you will need a light niche (housing) and a light assembly. It is necessary to get a light niche and light assembly that fit together properly. Traditionally, large niches were for pools and small niches were for spas, but some modern lights are bright enough for a pool but fit in a small light niche. There are different light niches for concrete (gunite), vinyl, and fiberglass pools or spas. If you have any problems finding the correct light niche and light assembly, please ask.