Wolf Tooth Elliptical Direct Mount Chainring - 38t SRAM Direct Mount 6mm Offset Drop-Stop B Flattop Compatible BLKDesigned to fit SRAM cranksets with removable spiders. Its proprietary design has an ovality of 10% and a timing of 112 degrees after top dead center which provide the beneifits of an oval ring such as greater rear wheel traction without the traditional downsides of oval rings. Elliptical rings provide smoother more efficient pedal rotation which means better traction Drop Stop chainrings are designed for use with 1x9 1x10 1x11 and 1x12 drivetrains