Our 9:ZERO:7 tapered headset is designed to work with a straight headtube 44mm frame and any tapered mountain bike fork. We specifically think that it is a great match with our older aluminum frames (135mm Slider, 190mm QR, and some 170mm QR).
Installed in my fatbike frame with a 44mm head tube and now I can run tapered steerer (1-1/8 to 1-1/2" taper). The headset is a quality part with sealed bearings and a split lower race which facilitates swapping of forks. The price is excellent (on clearance). Christophe on 18th Aug 2015