This is a New Reproduction of an Schwinn Stingray Seat Post with a diameter is 13/16" or 21.1 mm. The seat post is 14" Long with a 5/8"diameter top with nice chrome and solid Construction. This seat post was used on Vintage Schwinn Bicycles Pre 1980. This is a Schwinn Specific Size. This Seat post easily replaces the shorter seat post found on Vintage Schwinn Cruiser Bikes. Nice look and performance for your vintage bicycle restoration.