The phot r double super clamp is a unit of two super clamps made of lightweight cast alloy fastened together at a 90deg angle the clamp has many other uses within a photo studio clamps on tubes25 to 35cm in diameter this is a unit of two super clamps made of lightweight cast alloy fastened together at a fixed 90deg angle to provide extra strength support for tubes or bars perfect for holding a background crossbar on an autopole can be used for a variety of functions clamps on tubes