The Shadow Tripod seat post is designed to work Exclusively Tripod seats & uses a unique wedge system to allow two angles of seat by tightening just one bolt. Made from tough 6061 aluminium with an offset thickness tube for extra weight savings. PLEASE NOTE: WORKS ONLY WITH TRIPOD SEATS. section Product Specs TYPE: Tripod LENGTH: 135mm DIAMETER: 25.4mm WEIGHT: 110g / 3.9oz