X-Barrel barrel attachment connection. As used on the FX Impact-x, Impact MK2, Impact M3, Wildcat MK2, MK3, Dreamline, Maverick and Crown / Crown MK2 air rifles.

.177 (4.5mm) – 19960
.22 (5.5mm) – 19961
.25 (6.25mm) – 19962
.30 (7.62mm) – 19963