I got a set of the Axminster ones (600 mm) when thy ran a promotion last year. They went straight back as the sliding head wouldn't grip on the bar. To be fair to Axminster, they sent out replacement parts, even after the clamps had been returned, so I think the problem is sorted out now. Definitely not of the same quality or ease of use as K bodies, but they are much cheaper. I have traditional type sash cramps and a set of four 1000 mm K bodies...I always reach for the K bodies first. Unfortunately in the current financial climate, my money is staying safely in the old biscuit tin under the bed.