The 691 is a 1.370" x 24 TPI right-hand threaded tap designed for use with the BTS-1 Bottom Bracket Tapping Set to tap English threaded bottom bracket shells. This tap is used on the non-drive side (left side) of the bike.

• 1.370" x 24 TPI right-hand threading
• Sized for the English bottom bracket shell standard (also referred to as BSA, BSC, BC, ISO, British, or Euro)

NOTE: Always use cutting fluid such as Park Tool CF-2 when machining.