New to the brooks range the pre aged saddles have had extra treatment for the leather before being made into saddles this means that the saddle will take less time to break in perfect for older or recondition bicyclesas with the non pre aged model this saddle is identical in size to the b66 s however it is mounted on a single rather than a double rail so you can have the brooks comfort on a bicycle fitted with the more modern micro adjust seat post a single rail frame also gives a sl