I bought the 25L trailblazer to wear on my day hikes. I carry waterproofs in it, spare socks, trousers, dart shirt, and a protium jacket as well as packed lunch. Wallet, car keys go in the lid internal pocket.
In the two side pouches I carry a Flask or bottle each side. The 2 side strap pockets I usually cram with on the go snacks such as apples and nut bars etc. When I get hot I can cram in my thick fleece into the sack as well with ease.
It's a very comfortable back pack which you can adjust to wear high or low on your back, tight or hanging off your back. The choice is yours and its easy to adjust as you stroll along.
The draw string arrangement on the knapsack is excellent. So easy to draw super tight or loosen to its full stretch with minimal effort (none).
The front chest straps are height adjustable so you get the placement you want. Once adjusted you don't get all those straps flapping about as you walk
A great day back pack comfortable and practical. If you want to carry a tent, spare boots etc for longer treks I'd go for a larger capacity.
Great design for those day hikes.