I thought I should give you some feedback about the hydration system I bought last week at the Kielder Ultra. It is absolutely brilliant. I used it today at the Hawkshead trail race (16k), where I wanted my hands free to use poles because of the steep ascents and descents. The positioning of the water bottles is perfect for me and I hardly noticed they were there ( 2 x 500 ml as supplied). The material is very light weight, and the pack is easy to get on and off. The long thin shape of the bottles means that they stay secure in their pouch and are carried high enough up to make it very easy to access on the run. Everything is secure and the bottles do not bounce around. There is enough space in the back for first aid kit/emergency blanket (as well as mandatory kit) - which was just as well as both needed to assist a fellow runner who had a serious fall. This is just what I have been looking for for nearly 10 years - I have a collection of vests and race packs but none (from big brand names) have the water in the right place. So well done to whoever designed it. Definitely a five star product.