The Dome Port Cover S is made of neoprene as same as wet suits. It is recommended to put it on the Dome Lens Unit III all the time to prevent accidental damage whenever not in use. The Dome Port Cover S has slits on its top and bottom for integrated shades to help easy and speedy installation/removal.
 

*Never put wet cover on the Dome Lens Unit III on land. Doing so may cause degradation of the lens coating or glass itself resulting in spotting or discoloration.