FX airguns 28mm shroud tubes in various lengths. This is just the tube no fittings.
We have tried to compile a list of which tubes are for which barrel lengths, but if in doubt please measure your rifle:

19131 – 157mm – Impact Compact MK1 MK2 & M3 & M4
19573 – 230mm – Wildcat MK1 MK2 & MK3 500mm, Maverick Compact
19692 – 270mm – Impact MK1 MK2, M3 & M4 500mm & 600mm,
19099 – 345mm – Boss, Royale, Wildcat MK1 MK2 & MK3 600mm, Maverick 600mm
19328 – 362.5mm – Impact MK1 MK2, M3 & M4 700mm
19142 – 447mm – Impact MK1 MK2, M3 & M4 800mm, Crown (measure), Wildcat MK1 MK2 & MK3 700mm, Maverick 700mm

Different versions also fit; Indy, Independence, Verminator MK2, GLadiator MK2