I made these in 1979 based on something I saw driving past a worksite. They still work well, 'tho worn almost an inch shorter from being dragged around on concrete.
A few years ago someone gave me scraps of nice plywood so I made more, thinking I would sell them, but they got put to use instead. The picture shows the four standing heights possible. A hammer claw easily picks one up without bending. They get used a lot during moves of heavy things to get a partial lift.
Anyway, out for a walk I saw this at the site of a nice fence being built. Probably 20" tall, which is a pretty huge step up- mine are 16".
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