ProX T-SAAC Crank System Adjustable Speaker-Subwoofer Pole 1-3/8" diameter - from 34"-52"The ProX T SAA M is exactly what you need for your subwoofer speaker PA system. It's adjustable in height from 38" to 54" and mounts between a subwoofer cabinet with a top mounting hole and a speaker with a bottom mounting hole sized at 1 3 8" (35mm). The T SAA M features both a friction locking knob and a security pin system and is made from durable steel. Features: Heavy duty steel construction Height adjustable from 38" to 54" Friction locking knob