Gregory’s latest mid-size day pack, the Z22, is perfect for mountain trekking, peak bagging, adventure racing, and the like. I’ve tested it this spring and summer during several adventures, and I’ve come to appreciate its skimmed-down design: Just one big main pocket with a hydration sleeve; a small zipper pocket on top; and stretchy mesh outer pockets for random extras.

Oh, and there’s the requite hip-belt stash pockets for storing sunscreen, food, salt pills, and other need-now necessities. (For most adventures, I won’t wear a pack without hip-belt pockets anymore.)

But what makes the little pack unique is its new suspension system, which allows air to circulate behind the back panel, between the pack body and your back, thus keeping you cooler.

Or so the theory goes.

Called the “Jet Stream Dynamic Transfer System,” Gregory’s air-flow back panel area props the pack slightly off your back just like Deuter and a couple other companies have been doing for years.

This diagram (sort of) demonstrates the principle:

But the “Jet Stream Dynamic Transfer System” is a bit unique, as it has a tensioning system that stiffens the frame—and offers more support—when more weight is loaded into the pack, doing double duty to keep the pack off your back while also dynamically adjusting with the weight in your pack.

The Z22’s harness system is mounted to the main pack on crisscrossing bars. They flex and push out off the pack—thus maintaining the air pocket—when more weight is added.

For me, the pack carries well and has most of the components I need on a day hike or quick adventure.

Sitting empty, the pack weighs 2 pounds, 10 ounces.

But it comfortably carried about 20 to 25 pounds in my tests, and the suspension system/air-flow area seemed to do its job.

No complaints.

$99

www.gregorypacks.com