Excellent quality and finish. Two of these clamps hold an 80mm Refractor rock solid on top of a 120mm Refractor.
The clamps are of good quality, similar to other types of clamps, which fit type "D" dovetail plates. The OPT website lists these as being on backorder. This is true, as I waited in excess of 1 month to receive mine. Should you decide to order these, be aware that the backorder time could be quite lengthy. There are similar alternatives out there, which might be available in shorter times.