The basic jack is just one short (1 foot) tube, no holes. There is another Product that comes with an adjustable extension tube (holes to adjust)
Used them to level a floor.
Yes, but if you’re in sandy soil, I recommend you do like I did and put down a 18” x 18” paver, then use your cinder blocks. You will have to use 2 of these jacks separated by a short distance on each beam, unless you use a hydraulic jack to raise the beam because the jacks don’t have enough leverage to lift the house.
In the wall? I've only used them under the floor beams. If you need them in a wall I would think you need them under the wall or maybe I'm not understanding your issue.
I used mine under my deck to level my hot tub
not sure. mine is in the crawl space to lift one side of my sagging door frame not sure its weight rating.
Yes, if within the height from floor to slat. Could screw upper plate to slat to ensure it does not slip.
Not sure mine is in a crawl space out of sight it probably will its stamped steel if left outside.
I ordered mine online and I had them shipped to my house. They were delivered 6 days from when I ordered them. Very easy to use and have done the job I needed them to do.
these are not intended to be the main support, but I used them for extra support in a crawlspace on a 1927 cabin in areas where we heavy appliances and a wood burning stove. They indeed, solved some of our issues.