The S-Lever tightens and loosens the friction tensioning knob with ease for fine adjustment control. This add-on allows you to allow you to tilt or cant your rifle side to side to level your crosshairs by replacing the friction tensioning knob on Harris and Caldwell XLA "S" type bipods. Made of fiber reinforced nylon, the S-Lever is designed to flex or break off if it gets over-tightened or hung up on something in the field. Installs easily... Just unscrew the friction nut and replace with an S-Lever.