CowCow RM1 Stainless Steel Guide Rod For Hi-Capa 4.3 & 5.1

- Stainless Steel material with CNC machined- Drop-in 2nd spring and additional spring housing design- 3 different wright of recoil springs for precise calibration - Combine with primary spring to soften recoil- Enhanced the reaction force to speed up to blow-back cycle- NOTE: As always, upgrading GBB require necessary skill & technique, consult expertise if needed