I used a Pop Up 28 last fall, and found it to be a great pack.
It’s out of the way when busting brush, spotting from prone, or drawing a bow, but large enough to carry plenty of crap for a day hunt. Capable of hauling decent loads with the frame extended. I also like that the pack is built with stout enough material that I don’t mind throwing it in the back of a pickup and letting it bounce around.
