Magura rotors utilize a 2.0mm thickness for optimum performance All Storm rotors are Magura's Mission Performance approved. Storm SL.2 and Storm HC rotors feature 15% percent less weight with improved self cooling and outstanding performance in every condition Storm HC: Designed for extreme use for unparalleled braking performance under high braking forces Storm SL.2: Large ventilation and formed perforations throughout produces significant weight reductions and an optimal feel 6-bolt rotors include: (1) 6-bolt/44mmBCD rotor with (6) T-25 rotor mounting bolts 100g Storm SL.2, 127g Storm HC at 160mm