It depends on the type, but lens attachments are camera lens accessories that are mounted on the lens to provide a function it didn't previously have. Samy's carries a variety of these accessories, including teleconverters to increase the lens focal range, lens adapters that allow you to use a photography lens on a camera body it was not originally made to work with, and lens filters to either protect your camera lens from damage or enhance the lens's light performance among other functions.