These hardware kits were designed for Easton's side clamping system on their ISA seatpost designs in both the EC90 and EC70 versions. Two options are available, one plate kit for oversized oval saddle rails, and one for 7mm round rails. Made of aluminum, and clearly marked for the intended use, these simple hardware kits are all you need to change your post head for desired saddle rail compatibility. You are intended to use the rest of the existing hardware that comes with your post.