The Deluxe Signal Tube lets you fill the tube at depth by holding the open bottom of the tube over a regulator mouthpiece while the regulator is being purged. When the tube is sufficiently filled with air, the diver can release it to the surface (while tied to a line) a built-in Over Pressure Relief Valve allows the tube to ascend without rupturing. There is also an oral inflate valve for surface use. Measures 7? wide x 60? tall. Develops 22 lbs of lift in fresh water.