These two-bolt seat posts have a generous 30mm of setback, among the longest ever. This is very important for those who ride leather saddles that often have little fore-and-aft adjustment due to the short rails. 

The VO seatpost is internally ovalized to reduce weight to 301g. The adjustment is from the bottom, and the two-bolt design makes it easy to precisely adjust the seat angle. Also note that the head is integral with the post, not pressed on as on many modern posts. This makes them stronger and lighter. 

27.2mm only x 300mm. Maximum height (above the min. insert line) is about 23cm.