If you are the type of biker who brings extra water bottle on every ride, the Ryder Water Bottle Seatpost Clamps will allow you to put extra water bottle cage on your seat post.
It is suitable for mountain bikes and road bikes. The bolts and nuts are made from anti-rust steel. The main body is made from lightweight cold forged aluminum.
Sizes available are 27.2, 30.9, and 31.6mm seatposts.