Wolf Tooth Elliptical Direct Mount Chainring - 42t, SRAM Direct Mount, 6mm Offset, Drop-Stop B, Flattop Compatible,Designed 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. Compatible with 12 speed SRAM Flattop chain Elliptical rings provide smoother, more efficient pedal rotation, which means better traction Drop Stop chainrings are designed for