Snap BMX Products S2 Fixed Seat Post Clamp.  Precision CNC machined from USA mill certified 6061-T6 billet aluminum. Stylish design.  Comes with 18-8 stainless steel screw.  Size : 31.8mm (large hole) fits frame post.  Small hole fits 27.2mm seat post.  Color - Black Anodized.  Weight - 1.2 oz.