Ultramount Junior has the same beefy 3\16" thick steel construction as the standard Ultramount, however, the Junior is only 7.5" tall instead of 9 3/4".
Footprint of the mount is 10 1/2" wide by 9" deep.
Standard dedicated Ultramount plates cross over to Ultramount Junior as well, so you can swap top plates if you choose to switch presses.
(Note) With Ultramount Junior being only 7.5" tall, most press linkages will hang below the benchtop to impede opening of cabinet doors or drawers (If you have them) below your bench. If you have any doubt, before placing an order, measure the linkages hanging down below your bench top and subtract 7.5".
If you want to have the press completely on top of the bench, the standard 9 3/4" tall Ultramount will fix you up perfectly.