I bought the Katari 1.5 pack to extend my range on gravel bike rides. The pack is fairly lightweight, even when full of water. 1.5 liters is enough to keep me going for a couple hours, but not enough to weigh me down. The shoulder straps and chest strap are adjustable to fit securely. The pocket on the outside of the pack is small, just big enough for a couple energy bars and some keys. You can slide a few larger items in the pouch with the water pack, but it is not as easy to access. The magnet on the water tube makes reattaching it after taking a drink very easy.