They sorta work. I mean when I had one on my wrist it seemed to keep the mosquitos away from the upper half of my body but they still attacked my legs. I will also say in reference to what other people were saying about the bracelets falling off, they don't stay on but only if you don't push the peg thing in all the way. You have to make sure it locks properly but once it's locked in, it stays on without an issue.
As for the reusability of the bracelet, I don't have a doubt that you would be able to use it again as it's a very strong smell. Probably good until for a few uses depending on how long you keep them on for. I only had mine on for an hour or two.