Description Guarder SP120 Full Tune-Up Kit for TM M4-A1 Series (FTK-40) SP120 Spring (Oil Quenched/Tempered Si-Cr Alloy Steel Wire) Polycarbonate Piston Air Seal Nozzle Ball Bearings Spring Guide Polycarbonate Ventilation Piston Head Stainless Cylinder Head Lucid Chromium Plating Cylinder Original Type Steel Gear Enhanced Tappet 6mm Steel Bushing Shim Set