The Aero Seat Posts and Aero QR Seat Post Clamps come in 2 sizes :
25.4mm Aero Seat Post and Aero QR Seat Clamp fit Chase RSP 3.0 Mini, Junior, and Expert size frames
27.2mm Aero Seat Post and Aero QR Seat Clamp fit Chase RSP 3.0 Expert XL and above sized frames
ALSO AVAILABLE :
AERO SEAT POST EXTENDERS allows you to raise your existing Aero seat post an for post race cool down rides or when cruising around.