Very cheap. I literally pulled the threads off with ease on the first clamp I touched and don't use any other clamps. As another review says, "Good for small jobs, not heavy jobs." I don't know what they're supposed to be good for, though. Spend the extra money on better ones or just choose a different manufacturer. I did not contact the company as it was my fault for spending under $10 on something I wanted to be durable and good quality.