B-Labs / Bionicon Oval Chainring Sram GXP Direct Mount 28t virtual range - elliptical shape simulates -2 / + 2 teeth as you ride Narrow/wide alternating tooth profile for ultimate chain retention offset chainline - mounting position to optimised for 2 or 3 ring cranks high-strength 7075-T6 Aluminium alloy - black anodized laser finish !!!!See charts in images to be sure you get the right ring!!!