The lenscoat lens cover for the sigma 150 500mm lens covers the lens with a 100 closed cell neoprene coat offering protection from bumps jars and nicks it also helps break up the shape of your lens making it less noticeable to wildlife and allowing you to blend in with your surroundings making it ideal for nature and outdoor photographers lenscoats are also useful for sports photographers and photojournalists who spend a lot of time exposed to the elements as they are waterproof and also