RMS Modular Spring 4+ J Spring SRS / TAC41 / SSG / VSRDescription A high quality spring machined in Europe by Rapax for SRS, VSR, TAC41, SSG, and similar sniper rifle replicas. Characterized by a slightly harder pull but suppressed mechanical action, the 13mm outer diameter spring comes with two spacers and an approximal power of 4J. The 3D printed spacers provide a non invasive option to adjust FPS Joule output. The product is CNC coiled from high quality wire, tempered, and furtherly electroplated.