Love these! I live in Chicago and use these every week for grocery shopping. I've used them since October 2015 on a once or twice-a-week basis.They clip on with a small "S" hook (attached to a bungie) anywhere and then 2 hooks wrap over a bike pannier rack's sides.I have read people having issues of hitting bumps and the pannier unhinging from the rack. I don't know what size holes people are riding over, but I have hit some small potholes and even coming off of a curb and they stay hinged. Mind you it's only as tight as the bungie cord, but you could even secure them tighter with zip ties or some other contraption if this is an issue for you.I've taken home $100-$150 of groceries (I'm not going to guess on weight) and have not had any issues of anything breaking or stretching. I've taken home 96 oz orange juices, packages of meats, pounds of flour, 48 oz milk, dozen eggs, etc.. It all holds up fine.After researching panniers, I thought I'd have to spend hundreds on one alone and then break the bank on purchasing a second one, but for $60, these are working for me just great. I think, even if I get only 5 years out of them, I've saved money.Pros:Folds up when not in useWide open space for ease of packaging itemsGreat price (compare it to others from a bike shop)Sturdy and can handle groceries for 2 for a week.LightweightEasy release to take into stores so they don't get stolen.Snaps closed when not in use so they don't hang out and catch on something.Cons:Materials to attach to rack- I'm sure the Bungie cords will eventually stretch out, but replacing them would be so simple. Also, the hooks that hang on the bike rack may bend in time with weight, but even then they could be bent back into shape or modified easily.Not enclosed- No cover for rainy days