Excellent for shorter off-road or slightly longer gravel runs. A 1.5 l bag is enough and everything else you need can be conveniently carried along. I am particularly pleased that even a large iPhone can fit in the front pocket.
Verified buyer

When you don’t want to carry anything extra, a small bike pack like this may be the right choice. Total volume 4 liters, of which the filled bladder takes 1.5. The shoulder straps have pockets for separately available QuickStow bottles.
The pack sits quite high up your back. The idea is to keep your riding jersey’s back pockets in use even when carrying the pack.