Ethic really wanted to improve the next clamp they csme out with so they changed the whole design giving the Ethic Sylphe a much more apealing look. With cut outs to the new design, this double clamp is much lightr than the previous one. Keep in mind that they did make TWO versions to this ONE clamp. There is the standard version that ONLY fits STANDARD bars and weighs 1.4 ounces and theres the oversized version that ONLY fits OVERSIZED bars and weighs also 1.4 ounces. Both include 2x 6mm bolts. 31.8mm is compatable with standard bars with a slit using IHC, ICS, MINI HIC or threaded compression. 34.9mm is compatable with oversized bars with a slit using HIC or IHC with OVERSIZED or ALUMINUM bars.