The 21339 Distance Rod with Hand Crank from K&M is made from solid steel tubing and used to connect satellite systems. Height-adjustment is by hand crank and extra safety features provided by additional push-button and locking screw, to avoid uncontrolled reverse motion. This product is the same as the K&M 21338, but with thread bolt M20 for connector plate 24116 for zero backlash and absolute vertical position.