I found these kind of by accident and glad I did. I ordered a pair (and the seller is wonderful to work with) and got them quickly. I quickly put them to good use. They are well made. The adjustment is smooth and sensitive to the touch. Between the weight and the magnet they are stout and steady as they hold the PCB firm. I am looking forward to bringing them to the next makers meeting. I didn't really rate the documentation as the instrument pretty much explains itself.