The dronecrates P3 backpack is awesome. It has a custom slot for 2 camelback bladders, (or you could fit a macbook or iPad pro in there) The waist strap is comfortable and removable, there are many pockets and you can clip whatever with a carabiner to the outside anywhere. The foam is water jet cut and with outside pockets empty it is carry on size. Also the zippers are the best zippers I have ever seen. Kris is the President/Owner and he is awesome to deal with. I had my P3 backpack for a little over a month and then the P4 was announced, he let me return it (60 day return policy) and now I am waiting for the P4 version to be released next month.
I hiked Mt Whitney with this one we just launched. It was pretty comfortable, I like that this one is a soft shell and not rigid like some of the others. I had two 32 oz Nalgene bottles, lunch, rain shell, 3 batteries. I think a light shell jacket would have fit in, but not a heavy jacket.
