"Over the years we've used Irwin proclamps and found them very good. Unfortunately in the last few years they have changed the design from the excellent Mark 1 version to a new Mark 2 version. This latest version is just about ok at first but after relatively little use begins to slip even when applying only moderate clamping pressure. It's missing a crucial locking piece compared to the original design. Since it slips and therefore doesn't clamp, it's no good and I would advise you not to buy it. If you know of any alternative equivalents I would be interested to know."