Designed with a focus on component robustness, the GPM XRTDP shock absorber shaft core kit employs 4140 medium carbon steel and 7075 aluminium to raise structural strength. The shaft core diameter increases from 5.0mm to 7.0mm, which reduces flex and extends part life under repeated loads. This kit is compatible with both GPM and original shock assemblies and is intended for hobbyists seeking a durable suspension baseline.