Gregory Zulu 45

Backcountry.com says:
Built for overnight backpacking trips, Gregory's Zulu 45L Backpack puts comfort forward. The ventilated back panel creates open space that aerates our back and lets heat escape while the FreeFloat suspension flexes with our body for a comfortable, body-hugging fit that's designed to prevent chafing. We like the large U-Zip opening for easy access to our gear and also like all the external pockets that Gregory packed into the Zulu—the extra-large zippered hip belt pockets, front stretch-mesh pocket, dual mesh side pockets, and top zippered pocket on the floating lid. That gives us plenty of places to stuff our gear for an overnight backpacking trip to our favorite forest, mountain, or park. The 45-liter pack can carry up to 40 pounds, but it's best for overnight trips with less gear to pack.