I would say they look plenty durable. They are cheap and easy to mount which is a benefit them and they have been making them for quite a while. I just stuck my bike upsidedown in a the dark house and spun the wheel. For the $6 or so bucks on ebay they are probably worth it. Get a bunch of batteries and you would be set. I wish there was a way to turn them off, but oh well. I do feel more comfortable at night with something else flashing especially to make me visible from the side. I usually take the bike paths at night except in my neighborhood that I am very familiar with and its only a few blocks and bikers are very common.