- AL6061-T6 alloy quick-release seatpost clamp - Stainless steel bushing ensures smooth lever action - Adjustment knob allows for on-the-fly fine-tuning - Rounded edges and floating bolt/ovalized hole design protects carbon frames and seatposts - 28.6mm for 25.4mm seatpost and steel frame - 29.8mm for 27.2mm seatpost and chromoly frame - 31.8mm for 27.2mm seatpost and aluminum frame - 34.9mm for 30.9mm seatpost and aluminum frame, or 31.6mm seatpost and carbon frame - 16mm height