These are great clamps, they slide together quickly to tighten an object. I've used other brands but these are faster and easier. I've bought several 6" and 8" clamps but I can see the neck opening is the same. For maximum versatility you can buy an 8" and use it under a 4" yoke. The threaded hole is not only a great feature for accessories that you can buy ready-made, but you can create your own special design.