This dual extruder use the standard Jhead mount and will perfectly fit on a prusa air 2 from Mecano (http://www.thingiverse.com/thing:14204). Please follow the instructions below.This extruder works with: Mk7-like drive gear: 2x (works perfectly with qu-bd drive gear) nut m4 x 70 : 2x Pneufit 4mm : 4x PTFE 4 (o) x2 (i) mm : 50 cm (2x 25mm) Bearing 608ZZ : 2x Jhead MK5 : 2x Nema 17 : 2x Spring (> 3mm inside): 3x screw, nut, washer M3 and M4 Note on printed pieces: You will certainly need some support material to print the extruder. The Jheads mount have adjustable 3 points leveling like prusa standard bed with springs. Nuts are blocked which make the adjustments easier. 3 points is the best compromise to mounting defaults. I used Repetier to make dual prints which work really fine, and online EEPROM write makes the gaps calibrations inprinting really really easy. A version will follow for prusa V2 extruder mount on structure. The carriage look like a monster mask without wires, which makes it even awesome ^^ (even better with pneufits)