Amoeba (ARES) Stainless Piston for Compact Power Spring Bolt Aluminum Construction/ Stainless Steel piston head The popular Ares Amoeba Striker S1 (AS-01) finally gets reinforced parts for those who wish to upgrade their rifle to over 450fps without introducing significant amount of wear and tear. this is ensured to last even with much stronger springs, which could have been damaging to the original parts. It is suggested to be used with the ARES C.P.S.B. Stainless Steel Spring Guide (ARES-AM-CPSB-002-SG) - Sold Separate Suitable for ARES Amoeba 'STRIKER' S1 Sniper Rifle