Axle system conversion kits for Hope Pro2, Pro2 EVO, and Pro4 hubs Front: different kits convert 20x110mm thruaxle to 9x100mm quick release and 15x100mm thru-axle (axles and skewers sold separately) Rear: different kits convert 10x135mm quick release to 10x135mm bolton, 10/12x135mm thru-axle, or 12x142mm (X12) (thru-axle not included, use the one provided by frame manufacturer) Kits for Pro2 Evo hubs are compatible with new Pro4 hubs. Kits for Pro2 hubs are only for Pro2 hubs