Octane One Pivotal Seatpost Light & short seat post compatible with Pivotal saddles. Offered in the most popular MTB dirt/street diameter &8211; 27.2mm. This models means that you can slam your seat all the way down. Octane One Pivotal Seatpost Specifications: Seat post compatible with Pivotal system seats. Diameter: 27.2mm Length: 150mm Weight: ~115g Buy Octane One Pivotal Seatpost from Chain Reaction Cycles, the worlds largest online bicyle store.