IT'S GOOD Source makes similar bladders for at least two other outdoor companies (Deuter & Kathmandu) but keeps the best design features for itself. This bladder offers an upgraded bite valve that twists easily to allow or prevent the flow of water. It has a brilliant sliding closure that is exceptionally easy to use and very secure. You can remove the hose from the bladder with no leakage, which is really handy if you're refilling from a stream and don't want to remove the tube from your pack. It comes with antimicrobial treatment and it is exceptionally easy to clean. I personally prefer this kind of closure because it's so much easier to dry out before you pack it away (dry it upside down over an empty drinkd bottle).
VERDICT The best value and the best in test and frankly the best option for the majority of walkers. Easy to use, easy to clean and dry and easy to refill on the hill: a great choice.