마루이 M40A5용 강화 피스톤 입니다.

특히 시어랑 걸리는 부분이 Steel 입니다.

This piston is made by precision CNC process.  The piston body is made of polymer, and the piston bottom is made of stainless steel.  While this polymer has good strength with higher elasticity than the original part, the stainless steel bottom has strengthen construction.  Therefore, this piston  has higher durability.