Originally Posted by keen
They're not significantly different than the way many 2 post lifts are setup for truck adapters, which are also perfectly safe when used as designed.
Keen you make a lot of good points, the one comparing the floor jack extensions to a 2 post lift isn't one of them. A 2 post lift (I have one) has heavy structural arms that attach to the columns of the lift. The arms won't roll over like the floor jack will. And on a 4 post lift you have 4 points of contact for stability. Big difference, huge difference.