BMX Seatposts come in three different types - Railed, Pivotal or Tripod. Railed seats are more old school but they're making a come back with some companies upping the rail to titanium keeping things nice and light.
Pivotal is the by far the most popular seatpost type currently. Pivotal allows you to adjust the seat angle using the notches located on the post and on the seat. The pivotal type system can be installed using a 6mm allen key through the centre hole in the top of the Pivotal seat.
The Tripod type seatpost is quickly becoming popular due to being lightweight and clean looking. Below we shall look at all 3 types and explain in a little more detail how they work.