I've never used on. Had a jack slip on me yesterday as there wasn't much lift on.
Now I use an octagonal chunk of 2" thick softwood (made from a 2" X 4"). It fits inside the round receptacle on the jack. Inexpensive. The lift point on the car indents the wooden block..
Yes I use them on my floor jacks and jack stands....a hockey puck will work also...for the pinch weld on the side I cut a groove in the puck to fit the pinch weld..
I've never used on. Had a jack slip on me yesterday as there wasn't much lift on.