Paxman 25M B/F : Yellow Brass, Duall Bore System, detachable  Medium bell, Flipper, adjustable Fingerhook, minibal system, lacquered. 

The model 25 incorporates Paxman’s innovative Dual Bore system, where the F side of the horn uses a larger cylindrical bore. This opens out the F side, giving it a similar resistance to the shorter Bb side and allowing the player to push the air through in the lower register.