An optical-grade 6-inch diameter dome allows you to fully take advantage of the angle of view of your lens. Compared to glass, the acrylic front element makes it much lighter weight and easy to pack. Our unique zoom sleeves are simple and affordable, making it completely painless to use and travel with a variety of lenses. For most lenses, simply install the zoom sleeve between the port and the housing. Then slide your camera into the housing with lens attached. Zoom sleeves are particular to the lens for proper operation. Refer to the next section for information on which zoom sleeve you need for your lens. MIL Port System An interchangeable lens camera demands a housing with interchangeable lens ports. It couldn't be more simple to change ports than this sytem just press the port on and tighten three thumb screws. Feel positive reinforcement that the port is secure without any complex moving parts that can jam or break in a remote location.