Steel tube combination for use in subwoofers with M20 connection. The height is fixed with a safety hook and secured by a clamping screw for a vibration-free and firm fit. The slim design of the clamp allows space-saving transport and ensures a stylish appearance. The usable height is between 900 and 1,400 mm and is adjusted in 5 steps of 100 mm. The patented expanding mandrel with quick-release fastener ensures a tight fit. The plastic expanding splints also ensure a vibration-free connection between the speaker and the tube.