I have old-style Go-Jacks that I bought from Griot's Garage's warehouse clearance sale probably six years ago. They are great (although one of the jack ratchets sticks). I have the Harbor Freight style too, but if you have a car in the corner, you can't get a jack underneath on two sides. I often will put a car on Go Jacks, push it to the corner, then take two off so I don't trip over them and the car doesn't move.