JBL Professional JBL JBLPOLE Gas Assist Speaker M20 Threaded Lower End, 38mm Pole & 35mm Adapter Features an amazing height adjustment collar with an ergonomic "Z" knob that makes exact adjustments comfortable and easy The collar on the tripod leg fitting prevents over-tightening and breakage issues associated with all plastic designs, plus our die-cast fitting is 30x stronger than materials used by the competition Manufactured out of extruded double-drawn 6000 Series aluminum tubing, which makes the design incredibly strong but surprisingly light Fits all subwoofers with standard M20 threading; threaded sockets found on JBL PRX, VRX, STX and SRX818 subwoofers minimizes buzzing and rattling and assures that the pole will be secure and straight