Signswise Black 31.6*450mm Carbon Fiber Mountain Bike Bicycle Seatpost Seat Post Quick disassembling. Easy to install. Durable lightweight design. Can be used for a long time. Weight: About 270g; Size: 450*31.6mm Note one the seatpost is fit for the 31.6 mm bike frame so in order to install the seatpost successfully ,the seatpost outer diameter will little smaller than 31.6mm, so please pay attention to this information before you order it Note two :The bolts is screwed into the nut's hole slowly,when you are installing the seat post If you can not make it successfully,Please loosen it and screw it agains slowly. Screwing it forcely that will damage the nuts and bolts.