BB-5 bottom brackets for 2-inch track with outside hookup. The outside hookup style routes the cable on the outside of the bracket, which is what you need on low headroom installations where there is not enough clearance for standard inside hookup brackets. Made from 11 gauge steel with a drilled pin. Sold as a matched pair. If you've got a low headroom door on 2-inch track and the bottom brackets are beat up, make sure you are getting outside hookup style, not regular. They are heavier duty than the residential BB-100s.