White Industries external BSA style bottom brackets are made here in our shop with U.S. sourced 6061-T6 aluminum and feature Enduro stainless steel bearings as well as a ceramic bearing upgrade option where possible. We offer a wide variety of styles and colors to help you fit your favorite crank to your favorite bike. "BSA" bottom bracket shells and cups are named after the Birmingham Small Arms Company which created the thread standard used in this system. It's also referred to as "British" or "English" style and is the most common type of system found on modern bicycles. The "external" designation refers to the fact that the bearings will sit outboard of your frame's bottom bracket shell as opposed to being tucked inside the shell as you would find on some styles of BSA bottom brackets. - 1.37" x 24 TPI threads - Designed to be used on 68mm or 73mm wide bottom bracket shells - Internal BB sleeves are not available for our BSA bottom brackets - Installation torque spec is 26-37 ft lbs (35-50 Nm) Comes in sizes to fit: - White Industries MR30 cranks/Etc (30mm spindle) - SRAM DUB (29mm spindle) - Shimano HollowTech II (24mm spindle) Cup weights - 30mm: 77-82g - 29mm: 85-90g - 24mm: 80-85g