Haro Premium Pivotal seat post is a must for those who want a bit lighter post and also a post that grips the seat rails a bit more firmly than tradition seat post clamp type.   The width is 25.4 which fit most all steel bmx bikes.   Aluminum race bikes take a different size.  You must use a pivotal seat for this to be complete.  The length is 200 m.m. which is plenty long for most bmx cyclists.  It is an aluminum post.   Quality from Haro Premium.   Thank you for supporting a small business.   Please visit my store bike lady on ebay.   We have many bmx parts available.