SRAM's size Medium disc brake pads come with several compound options including, metal sintered with steel backing, organic with steel backing, or organic with aluminium backing and are suitable for SRAM Guide, Level Stealth 4-Piston, G2 and Avid Trail disc brakes. Compatibility Medium brake pads are exclusive to our mountain bike line of brakes and cover the aggressive cross-country rider up to all mountain riders. The brake models that they cover are: Level Stealth 4P Ultimate (A1) 2023+, Level Stealth 4P Silver (A1) 2023+, Level Stealth 4P Bronze (A1) 2023+ G2 R, RS, RSC, Ultimate (A1) 2020+ Guide R, RS, RSC, Ultimate (A1 & B1) 2015-2020 Avid Trail Compounds A choice of 4 compounds are available. Quiet/Organic - SRAM code: 00.5318.003.004 Quiet+Light/Organic - SRAM code: 00.5318.003.003 Powerful/Organic - SRAM code: 00.5318.003.006 (these come on new Level Stealth and G2 brakes) Heavy Duty/Sintered - SRAM code: 00.5318.003.005 (these come on new SRAM Guide brakes) For more info you can check out SRAMs brake pad page