Chromag sequence bb30 direct mount chainringthe sequence chainring uses the official x sync technology licensed from sram for unmatched chain retention chromag is the only mtb company officially authorised to produce chainrings with the x sync technology so now no matter what kind of mountain bike you have you can have the peace of mind that your chain will stay put features material 7075 t6 aluminium official sram x sync technology complies with sram warranty standards for compatibility w