The BBT-29 is a double-ended bottom bracket wrench designed to fit non-standard diameter 16-notch external bottom bracket bearing cups One end fits cups with an outside diameter of 39 mm such as Shimano Dura-Ace 9000 series & XTR 980 series The other fits 16-notch bearing cups with an outside diameter of 48.5 mm such as FSA Mega Evo Made in the USA & covered by Park Tools legendary limited lifetime warranty