I see an interesting mounting feature, the vise leg looks to be support horizontally off of a bench leg, plenty beefy looking, but maybe an indication that these aren't intended for significant hammer work. I'd bet it's kind of nice not having a toe stubber down there, and lets the folks not have to reach or lean as much.
Similar to how I devised a mount for my old post vise in my gunshop some 20-25 years ago. I realized the importance of getting it up to elbow level, so I just built the whole mounting island for it out of steel, cut floorboards out of the shop floor, dug a hole in the ground beneath with post hole diggers, and set the whole rig in the hole and poured concrete around it. Then I carefully replaced the floorboards around it. Didn't realize at the time how nice it would be to be able to work all the way around it and not stub my toe on the leg. Bottom of the leg on mine is at least 10" off the floor.
Doesn't require a lot of bulk to brace that long leg solidly. It's length works as leverage for stability.
SRH
