The direct mount chainrings for SRAM cranksets replace your existing spider and chainring with one clean looking, lightweight, and stiff piece of machined billet. They are available in 3 different offsets: standard 6mm offset, Boost 3mm offset, and BB30 short spindle 0mm offset. Compatibility: These direct mount chainrings will replace your existing chainring and spider or replace the direct mount ring on SRAM cranksets including the DUB cranks. The ring is attached via 3 bolts on the back side of the spider near the spindle. Note that the SRAM 12spd Red and Force AXS use a different 8 bolt mounting interface that is not compatible with these chainrings. Wolf Tooth’s patented Drop-Stop® wide/narrow tooth profile for the ultimate chain retention and mud shedding ability Fat bikes: If your fat bike has a 170/177 rear hub spacing, use the standard 6mm offset Praxis Works Road/CX cranks use the 6mm offset. Praxis Works mountain cranks use the 3mm offset for their DM-A and 0mm offset for their DM-B chainrings. There are 3 offsets: Standard Road/CX/Gravel: 6mm offset for cyclocross and road crank applications with 47mm chainline Standard MTB: 6mm offset for non-Boost mountain bikes, GXP and long spindle BB30 cranks for 49mm chainline Boost: 3mm offset for 52mm chainline BB30: 0mm offset for BB30 short spindle cranks for 49mm chainline *40T ring image shown. MODEL ITEM #: SDM40-FT (40T) SDM42-FT (42T)