Jack Clamp - Jack Clamps Lowell Thomas Tools (Rating: 5)

Bought these last year and have had good success with these. They grip better than any other clamps that have this type of hand pull. I used their spreading feature on a bench I put together this weekend and it was so easy making small changes in height. Very easy to dial in to exact dimensions and very well built. Built in the USA with a lifetime guaranty. I have no affiliation but I do know I'm going to order another set.
They also are rated at 300 lbs lifting. I debated long and hard about these clamps because they looked like all the other clamps I have. Once I opened the box I knew right away they were different and I made the right choice. Built like a tank and built in Montana..they gotta be tough.
There's some videos on their different uses. I have a Supermax sander that needs to be lifted and it weighs 287 lbs so once I figure out how to get some kind of sling set up for lifting it I'll send some more pictures.