- Replaces the existing chainring and spider on 3-bolt BB30 cranks or SuperBoost chainline - Features Drop-Stop tooth design to prevent unwanted chain drop - Fits SRAM and other 3-bolt cranks - Flat ring provides 50mm chainline on SRAM BB30 / PF30 short spindle (has 9.1mm drive side spacer) - Drop-Stop B rings are compatible with 10/11/SRAM 12sp chain and Flat Top/Transmission chains. Not compatible with Shimano 12 speed - Made in the USA from 7075-T6 aluminum alloy.