The O-Ring Piston kit is designed to be a quick and easy replacement to the piston lid system found in stock KJW M4 GBBRs. It increases durability by eliminating piston lid cracking which is quite common.

Features

1. -6061 T-6 Aluminum body with Buna-N O-ring
   

2. -Machined in the USA
   

3. -Includes spare O-ring

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