QUOTE(RKramden @ Dec 15 2022, 11:50 AM)

I beleive these jacks and stackers might require a bit more work that just bolting them down to the Garage floor. First off, residential garage floors are a crap shoot, usually no rebar and could be minimal concrete (thickness and PSI). Plus they usually slope to the door. The two posts must require some type of footing. Not sure what if any type of laterial loads these can take, but all that force goes down to the base plate and bolts. I live in California and would have a hard time leaving my precious metal stacked on top of each other just hoping that today is not the day for the big one.
You are right, the state of the concrete is very important for a two post. A two post would have to have better flooring to support any bending forces from an uneven weight. A four post not so much. From what I have read there is alignment that has to be considered also on a four post. I think they put in wedged shims if it is badly out of true.
If you look at the base plates, the contact area is the same or bigger than the contact patch of my truck's tires. So far the truck has not gone through the floor so it is unlikely a four post with a 914 on it will either. There are people who install these professionally and have put in many units. This is the way I would go. I don't need to make a mistake and learn the hard way. Of course where I live it doesn't need to be seismically qualified.
The Garags price does seem to scream SCAM... With free shipping? Yeah, right.
All they want are your credit card details... bait and hook.