The Sigma LCF 55 III offers protection from external impacts like scratches and abrasions to the camera with its hard plastic covering. It also protects the lens from harmful UV rays of the sun when the camera is not in use. It has a diameter of 55mm and is compatible with Global Vision lenses. It is very easy to open and close; just a gentle push of the button will remove the cap. This feature helps to click photos instantly without missing the moment you desired to capture.