Trijicon ACOG 4x32 BAC Riflescope and the cylinder head has

and the cylinder head has a double o-rings outside

soak the gel balls for 2-4 hours for growing to its full size

Compatible with standard 19mm outer barrels

Product Weight: 68 g

Trijicon ACOG 4x32 BAC Riflescope and the cylinder head hasThe Trijicon ACOG 4x32 BAC Riflescope is a professional's choice, with real fiber optics for quick target acquisition. It features 100% shock, recoil, fog proof and nitrogen filled construction, ensuring durability in harsh conditions. The glass edged reticle and multi coated lens provide sharp optics for precision shooting. Features: equipped with fiber optic sight for quick acquisition. 100% shock,recoil, fog proof & nitrogen filled. dual