For me, I wanted to be able to crawl underneath and work on my car, so I got quick Jack 7000lbs jacks. They go up to 26" high and I have full access to doing work underneath. Good Luck
The jack is just to lift the car. I wouldn't work under any jack without stands. (excluding a lift of course - but due to a herniated disk in my neck, i'd rather lay on my back to work on a car)
I see where your coming from. Even when I got the 7000lbs Quick Jacks I was nervous until I actually worked on it. I can push on the sides and it doesn't move. The Locking Rails are heavy duty thick steel. I got over it, but took a few times under car to feel I was pretty safe. And I am a very Safety Conscious person. Good Luck
Its the same reason i bought the quick jacks. To be honest that system put my mind at ease for working underneath of the car. I used to double up my jacking with stands and keeping the jack in place before but even that made me uncomfortable. Like you said having the lock rails is awesome. I have climbed inside the car, in the trunk while up on the jacks and its solid as a rock. I think what pushed me over the top was watching the testing video of a quick Jack 5000. It can hold a butt load of weight before failure..More than i would ever put on it.
