S&M Seatpost Clamp Quick Release 28.6mm I.D. for 25.4mm seatpost Experience a new level of efficiency with this S&M Seatpost Clamp Quick Release. The 28.6mm I.D. fits perfectly on 25.4mm seatposts, ensuring a secure and stable hold. Say goodbye to slipping and readjusting during rides, thanks to its reliable gripping power.