Projekt Fixie - Fixed Gear Mountain Bike Mtb Road Cycling Track Bike Seatpost Clamp Fixed Bolt Seat Clamp for Better Seatpost Security, Theft Prevention For 25.4mm/ 27.2mm Seatpost 28.6mm clamps fit 25.4mm seatposts; 31.8mm clamps fit 27.2 seatposts Road, BMX, Mountain, Fixed Gears, Fixies, Track, Singlespeed Bikes Compatible with other Projekt Fixie components