I have been using the same platy for 5 years. Because my pack is small I can't use the hydration pocket inside for fear of blowing out the platy. So I took a small hydration pack and modified it to hang off the shoulder straps of my backpack with key rings and clasps, the waist straps are tucked in and around my waist strap on the big pack. the hydration back has just enough room to keep snacks, hand sanitizer, camera,and a spare platy. I left one shoulder strap criscrossed on the hy. pack so I could sling it over my shoulder. This comes in handy when you have to trek a distanes for water on steep grades. It frees up 1 hand to use a hiking pole. I have been using this system for 4 years now. It works well with all my different backpacks.