I bought this as it said works with stainless up to 4". That couldnt be further from the truth. I was excited to receive this toolkit and I tried to use it on stainless 3-inch piping for my custom exhaust project. Pulling it out of the packaging everything seemed to be a quality material. I took it all apart lubricated all parts and went to town with my Ingersoll impact. I tried for about 10 minutes of on-and-off impacting to no avail. As you can see with the pipe below it is not expanded far enough to slip another pipe on.
If you're looking to do some stainless piping 3 inches or above save your money and buy a hydraulic unit instead
Edit: also to note, good luck trying to keep your pipe from spinning when impacting. I tried this with a pipe in my bench vise and it basically bent the end of the pipe that was clamped in...
Im sure this works perfectly for softer metal such as aluminum and steel pipe....stainless is too hard