e*thirteen Helix R Chainring - 30t 11/12-Speed 52/55mm Flip Flop CL 3.5mm Offset e*thirteen DM SilverE*thirteen QuickConnect Direct Mount rings include 1mm spacers, which allows them to be run on legacy cranks (TRS LG1 XCX), as well as Helix and Helix R cranks 3 bolt direct mount chainrings fit SRAM and other similar interface cranks Tooth profile is compatible with both Shimano and SRAM chains in both 11 and 12 speed Can be flipped to provide either a 52 or 55mm chainline TECH SPECS ring type single (anti chain drop) mount QuickConnect (E*Thirteen)