I bought these to help lift the dome on my observatory, which is extremely heavy. Before this, I had to drag out a large hydraulic floor jack and lift it from the outside whenever I needed to do maintenance. It was awkward and took a lot of effort.
These lifters made the job much easier. They give me precise control over the height, feel very solid, and are easy to adjust. I can now lift the dome exactly where I need it without wrestling with heavy equipment.
This is definitely a specialized use, but it worked perfectly for me. If you need to lift something heavy in a controlled way, these are incredibly handy and have already made maintenance much less of a chore.