This seat post is 31.8 mm in diameter and 19.7 inch (500 mm) in length. The material is aluminum alloy. It will fit our PR20S1 folding bikes.
To install your new seat post, just take off the existing seat post and replace it with this seat post. Then, push the seat post all the way into the frame socket until you can no longer see the minimum insertion mark. Make sure the quick-release handle is in a locked position on the bike frame.