I was able to purchase a Mantis brand new a couple of years ago. It does not get used too often so it sits where I first mounted it a couple of years ago.
This afternoon when I came to my bench it was laying on it's side, on top of my soldering stations. Broke the holder on both, but luckily it wasn't on the concrete floor.
Part of the base plate was still clamped to the table, the rest was still attached to the Mantis arm.
Nicely built arm made of aluminum, nicely built metal clamp, and thin plastic base. I have an e-mail in to Vision to see of there is a heavy duty base, because a replacement plastic part is $65. If they don't, I'm going to machine my own from aluminum.
Only posting so others can check for cracking in that plastic base before potentially losing your investment. It took me three years of saving and I'm lucky it isn't in pieces.