See: Mugen Seiki
Mugen Seiki introduces new shocks length adjustment gauge. The shocks length adjustment gauge is machined from anodized aluminum with a laser-etched measuring scale on the both sides. It is an ingenious new way for MBX7R, MBX7R ECO, MBX7TR, MBX7TR ECO to virtually eliminate chassis tweak by precisely matching the length and dampening rate of shocks. To set length, attach the adjustment gauge to the screw holding your shock and check if the lengths are identical.