Seatpost-bolt mount rear cable hanger (housing stop) for tradtitional cantilevers and centerpull caliper brakes.
Mounts on seatpost bolts up to 6 mm in diameter. If your seatpost bolt is thicker, you'll need to drill or ream the hole out larger.
The tab that goes onto the seatpost bolt is 3 mm thick, make sure there's room to fit it between the "ears" on your bike.
No provision for an adjusting barrel. Adjustment screw on the bottom is primarily to adjust the angle for smooth cable routing.