I thought I found the clamp of my dreams. Bought 2 times. I thought we were something that could handle the hardships I would put them through. upset. They haven't done a single project using 1" x 1" square steel pipe. The tension knobs have failed on the thread. The "quick release" is clumsy and clumsy. They don't hold the material at 90 degrees. without the use of other vices and clamps. Spend your money elsewhere.