Clear anodized tubes have a machined wrench flat on one end for ease of adjustment. Tubes have .156" wall thickness, are available in two diameters and a variety of lengths. The 56400 series tubes are 7/8" in diameter and both ends are tapped 5/8", one RH and LH. The 56500 series tubes are 1" in diameter and both ends are tapped 3/4", one RH and one LH. 6061-T6 aluminum.