This is a counterweight balance arm to be used with an Ikelite underwater camera case that is using a compact dome lens with it. Improved over the original Ikelite unit where the camera can't sit on a desk with it. This specific design let you have a stable camera on your desk in-between the dives without the need to remove it each time. The rear sealed section help you to add some positive buoyancy in the rear section of the housing and the weight box in the front is able to fit up to a total of 1 pounds (0,45Kg) lead to perfectly balance your camera in the water based on your setup.