Expanded on one end to 2" I.D. to slip over a 2" O.D. tube to regulate or shut off air. Also available non-expanded for in-line applications. Weight is 2 ounces.
Very good part for the price. Simple, effective, functional, but not elegant. If was elegant it would cost 10x, though. Probably want to put some threadlocker on the allen head fastener before you install it.