About their use
These hydraulic bottle jacks are used to life a mobile home while it is being set in place or prepared for moving. The picture is of a 20 ton jack. Two 12 ton jacks will lift a singlewide. Surprisingly, they are not expensive.
I think that with some direction, more owners could level their own homes. The jacks should be positioned carefully and you should always have blocks in place to catch the home is it slips off the jacks. If it slips, the home will drop before you have time to notice, let alone move. It is amazing how fast this happens.