The 648L is a T47 (47mm x 1.0) left hand threaded standard guide for use when facing bottom bracket shells with the BFS-1 Bottom Bracket Facing Set and 690-XL Oversized FacerThis guide is used on the drive side (right side) of the bike - this side of the bike drive uses a counter-clockwise or left hand threadingTap GuideBFS-147mmx1648LUPC/EAN/GTIN: 763477013439