This shock tool is CNC machined from 6061 aluminum with a laser-etched measuring scale on the face. The pivoting gauge on the bottom of the tool is ball bearing supported for maximum precision. Simply mount the shock on and move the slider bar to the extended position, then slowly push it in to the compressed position. The pointer will graphically displace any variances and you will be able to address them as necessary. FEATURES: Hard-anodized aluminumBrass pivot gauge for maximum precisionLaser-etched measuring scaleFor all racers: 1/8 to 1/10-scaleREQUIREMENTS: For spring rate Kg/cmA appropriate Kg scale for the Spring you like to testCOMMENTS: You can test spring from Inner ID 8mm to 19mm