Area 1000 Version VI (6) piston by Systema. This piston is the same as the standard version 2 and 3 other then the fact it's missing the second tooth. This style piston is being uses in more and more AEG's to help with reliability issues.

This piston will work in any AEG that uses standard pistons too! In fact, Young's Army recommends this piston for all versions of AEG's.