Heavy Duty Design. Safety Pin. Strong Twist Lock-off. 20mm Screw Thread. 35mm Top PoleLength Min: 710mm Length Max: 1215mm Top Pole Diameter: 35mm Screw Thread: M20. A strong adjustable speaker pole with a 20mm screw fitting on one end. These are suitable for spacing Mid-Top cabinets from Sub Bass Speakers. The Large 20mm threaded end usually screws directly into the bass cabinet- with the Mid-Top cabinet sliding over the other 35mm End. This arrangement provides very stable adjustable speaker spacing. The poles are made from steel with a tough black finish.. speaker pole-speaker stand