The defendert m1 is compatible with all standard front forks including reverse arch designs the unique quick release attachment system integrates the defendert m1 seamlessly with the front of your bike defendert m2 has an ultra secure quick release mounting system that easily adjusts from 254 to 349mm easily fitting standard and oversized seat posts the two pivot arm articulates for improved tyre coverage and perfect bike fit a stiff engineering grade plastic support frame is co moulded to