Lixada Carbon Fiber Seat Post Clamp Lightweight 30.2mm / 34.9mm Cycling Accessory Carbon fiber clamp with a locking threaded nut. Solid and durable, good finish and lightweight. The clamp diameter in 30.2mm can be mounted to 27.2mm seat post. The clamp diameter in 34.9mm can be mounted to 30.8mm or 31.6mm seat post.