The Gregory Icarus Backpack offers a great multi-use day pack with additional space for your must have items.
A front organizer pocket, battery/wallet pocket, dual waistbelt pockets and side mesh pockets keep all your gear uncluttered and easy to find.
Durable construction made from combination 210 denier HT twill and siliconized G 30 fabric. Siliconized coated G 30 body fabric. 210D HT nylon reinforcements.
I took this on a bush whacking route up Ralston peak (east ridge), the route was a use trail following a forested ridge with some class three. I bumped the pack on just about everything while squeezing through trees and rocks. I found one small hole in the G30 fabric and pulled it in different directions, sure enough it actually sealed itself. It's obviously a delicate pack but that's what makes it so lightweight and comfortable. It's so light and comfortable it's hard not to recommend it, but for climbers and people who are rough on their gear I'd recommend something tougher. This pack is for people who want the most comfortable and lightweight daypack you can get. My REI flash pack is slightly lighter (and packable) but no where near as comfortable as the Icarus. Air flowed around my back, the pack sat well and didn't shift when scrabbling and climbing. I barely remembered I had it on, and I would forget if it wasn't for the water weight inside...