These precision-engineered aluminium rear adjustable spring dampers from GPM are designed to lower internal friction and manage shock loads for improved balance on the LOSI HAMMER REY U4 ROCK RACER. The assembly keeps the 1.8mm spring wire diameter and includes an enlarged shock shaft, thickened from 3.0mm to 4.0mm, to increase stiffness and reduce bend risk during heavy use. This configuration supports consistent damping response and longer component life under demanding conditions.