Our 510-46-RKC Interior Analog load scale kit is designed for tandem axle drive suspensions with one height control valve. After a loaded calibration at a certified ground scale, the gauge will reliably display the on-the-ground axle group weight in POUNDS (lbs). When properly calibrated and used, Right Weigh on-board load scales are the most valuable tool available for maintaining safe and legal axle weights. Corresponding air line installation kit included For Dual Height Control Valve suspensions, purchase the 919-MINI-M3 valve and 101-SK installation kit