SRAM/Truvativ X0 X9 Mountain Chainring Original equipment on SRAM and Truvativ cranks, they also work well with other drive trains. Features Supplied in Tru Vativ packaging SPECIFICATIONSVariant38T 104mm BCD GXPMFG#11. 6215. 188. 440Tooth Count38Ring Position/Type Outer Drivetrain Speeds10Chainring BCD104SPECIFICATIONSVariant39T 120mm BCD BB30MFG#11. 6215. 188. 270Tooth Count39Ring Position/Type Outer Drivetrain Speeds10Chainring BCD120 | Sram |Truvativ X0 X9 Mountain Chainring 39T 120Mm Bcd Bb30 | Aluminum