For day hikers committed to putting in big days on trail and out in the countryside, the Sirrus 36 offers rugged reliability matched with super breathable and comfortable suspension that makes each mile better than the last. 
The Airspeed back panel combined with the lumbar belt provides good ventilation and exceptional comfort. The female version even has a shortened and special back, designed for the female anatomy.
In the middle is a large, vertically placed zippered pocket, great for storing a jacket or other layer of clothing you want to have at your fingertips. A large pocket is also on the underside and separates the main drawer into two parts. The pockets are also on the lumbar belt, upper lid, on the lumbar belt … The side pockets on the lumbar belt are zipped and allow access to small snacks or the phone.
Very useful is the zipper on the side and through which you can access the interior.
A rain cover, which can come in handy in case of unexpected bad weather conditions, is included.
There are plenty of loops and straps on the outside: one ice ax loop, removable sleeping bag straps, side compression straps and a Stow-on-the-Go hiking pole attachment.
Sirrus 36 is compatible with all Hydraulics and Hydraulics LT water tanks.