And the most dangerous. Originally they were designed to fit a wheel drum with the car jacked and you'd slam a log onto the point and the rotation would screw itself into the log and slam it on the ground splitting the log.
Worked but WOW. They were soon banned but came back mounted on a frame and powered by a small gas engine with some guards installed.
A friend has one, table mounted and electric powered but I have to look the other way when he uses it.