Sram 94BCD Oval chainrings are designed for Sram X01, X1 and GX cranks. They feature exactly same oval shape as our other oval chainrings. If you would like to read about benefits of the oval chainring, please check our "oval 104bcd" model for full description. All 3 sizes have built-in M8 threaded standoffs to provide the ideal 1X chainline. They improve stock Sram chainline by 1mm. What size should I choose? * 30T Oval chainring has an ovality of 28/32T and is best for someone who uses currently 28 or 30T round ring. * 32T oval ring will suit best someone who uses 31 or 32T chainring currently. While pedaling, you will feel quite similar effort to the one riding round 31T ring ( the smallest diameter of the oval is 30T), but you will gain the speed similar to riding 33/34T chainring. * 34T Oval chainring has an ovality of 32/36T and is best for someone who uses currently 33 or 34T round ring. It is ideal for 1x 9/10/11 and Singlespeeds. Oval (elliptical) chainring does not compromise the work of clutch mechanism in rear derailleur(video at the bottom). It also does not require chain tensioner when using in singlespeed application. Riding out of saddle on the uphill will become more pleasant. Ovality of the chainring is only 11% and feels perfectly round when riding. These chainrings also help you to recover after knee injuries as pedaling becomes smoother and less exhausting. It is the most advanced oval chainring currently on the market. The most advanced, Patent Pending narrow/wide tooth profile ever produced, guarantee minimum 12 months of excellent chain retention capabilities! We mean it. Always use a new chain with a new chainring. .