I thought this seemed like a great idea & purchased one. I went riding and the top flew off & I ended up loosing both my CO2 inflator & a cartridge. More secure to stash your accessories in a zippered zip lock.
excellent utility. will fit cell phone or extra tube, etc. fits better in bottle cage than the product I used previously. would like to be able to get one in the length of a 20 oz bottle for extra storage for longer rides to the middle of nowhere.
I like using this over a bag under the seat. My post doesn't get scratched up, the weight is lower, and it's water-proof. It's also cheap and will never wear out. It does take up a mount, so won't work if you need to carry two bottles. It's also not all that big, but will fit large Lezyne multi-tool, road tube, tire lever, patch kit, two Rolaids, a wash cloth to keep everything from rattling around.)