The ENVE Aero Seatpost features a D-shaped design that enhances aerodynamics and compliance. Available in three lengths and two setback options, it offers a perfect fit for various frame sizes and riding positions. Please note this only works for the ENVE Fray and Melee. Designed specifically for ENVE Melee and Fray frames, this seatpost was developed using CFD and wind tunnel testing to deliver aerodynamic performance that&&';;s Real-World Fast. The Melee and Fray frames, with their refined tube shapes and D-shaped seatpost, work in harmony with ENVE&';s SES rims for optimized speed and efficiency. Features: Three seatpost lengths: 275mm, 350mm, 400mm Two setback options: 0mm or 20mm D-shaped design for aerodynamic optimization Built exclusively for ENVE Melee and ENVE Fray frames.