A tape light cover protects light strips from dust, airborne greases, and dirt. If the lens gets dirty, simply wipe it. Tape light covers do not change the IP rating of the light, although frosted channel covers cause a 3% max shift in kelvin and brightness, so keep this in mind if you buy a frosted cover. Each cover only works with a specific series of tape light, so make sure to get the right one for your lights.