These are my two. One is a protech which has the chained post cap doobin was referring to. As said a must really, males it so much easier to stabilise on a small machine, makes the hammer more efficient and I find a lot quicker than using a leg. I use mine on my own using a plumb line hanging on the post so thay I can see it's going in straight in both planes, and can easily adjust as it goes in rather than waiting for another man to communicate to me. It has to be offset really to avoid arm smacking the dipper, means I can bring it in close to the machine which is handy in a tight spot, has 180kg hammer and is fine on 2.8t digger. I reckon the next one I'll have the 210 kg hammer as confident it will handle that easily too.
The second one I had adapted to go on the smaller 1.8tmachine. The pulley design is better to lift the weights can mountit direct in lineas no arm to bang on the dipper. That has a 130kg hammer and is just ok at far reach