These are replacement spindles for our MARG30 series cranks that use a 30mm spindle. Refer to the chart below to see which spindle will work for your configuration. Specs: - Made from U.S. sourced 2024-T365 aluminum - Compatible with White Industries cranks only - Comes in 4 lengths: - R30/G30 spindle is for 68mm or 86mm bottom bracket shells Spindle 126.2mm total length - M30/A30 spindle is for 68mm/73mm or 86mm/92mm bottom bracket shells Spindle is 131.2mm total length - Fat Bike -100mm spindle is for 100mm bottom bracket shells only (will not fit 120mm shells) Spindle is 158.2mm total length For177mm rear axle spacing with 66.5mm chainlines - Fat Bike -100mm/120mm spindle is for 100mm or 120mm bottom bracket shells Spindle is 178.2mm total length For 197mm rear axle spacing with 76.5mm chainlines