Piston type pressure snubber. It resists clogging and are self cleaning. Five different sized pistons included with each snubber to ensure the correct amount of snubbing for virtually every application. Grade A and B pistons are applicable for Gases, grade B and C for Water, grade C and D for Light Oil, and grade E for Heavy Oil. Made of 316 stainless steel. 1/2" NPT male. 1.125" Hex. 0.625" Thread length. 1.875" Height.