My first impression of them was that they were very good quality, the elastic cord itself was very thick and heavy. I could see them holding my lid firmly in place. However, once I installed it, I came back 20 minutes later to find that the fastener holding it to the car cover had come loose. I've tried a few more times and each time for an hour or two it has loosened again, I've tightened the clamp as hard as I could and they still won't hold, at this point they're totally useless. And with no wind at all. I use them on a very small Mercedes sports car so it only gets worse on a big car.