In addition to the traditional single or double water tubes, these corner tubes help round out the anchoring on your pool deck. Many times corners are left un-anchored and wind can lift the un-anchored winter cover fabric. These corner tubes measure 2 ft. x 2 ft. and are designed to be placed at the corners of your inground pool to provide additional anchoring weight for your winter cover. Simply fill with your garden hose, close the no leak valve and place in the corner areas on top of the overlap winter pool cover material to protect from winter conditions.