Replacement complete valve seat for inside the bottle on the following air rifles. Includes the o-ring

FX Crown & Crown MK2
FX Boss
FX Gladiator & MK2
FX Verminator & MK2
FX Impact MK1, MK2, M3
FX Maverick
FX Royale
FX Verminator & MK2
FX Wildcat MK3 BT

Now the newer improved version but backwards compatible.

Video below to show replacement