Guarder Steel Valve Knocker for Marui/KJ G Series GBB Series
Replace the standard valve knocker of airsoft pistol magazine
Steel Construction
Design for Tokyo Marui G17, G18C, G26 / KJ Works G23 / G27 Series Airsoft Gas Blow Back GBB Pistol

As always, upgrading GBB require necessary skill & technique, consult expertise if needed