This is our heavy-duty universal mobile base, and it's exactly what you need if you have large machine tools that need to “go mobile”. Like our other mobile bases, this one increases and decreases size in one-inch increments. In the case of the PM-2500, you can make the base a 12x12 inch square all the way to 36x36 (inches), and can also make as rectangle mobile base up to 20x52 (inches). And with a heavy duty weight capacity of 650 lbs. and ball-bearing casters/wheels, it'll handle virtually any tool, machine, or other item (safes, toolboxes, etc.) In addition, you can add to this with optional larger rails (part # K1218.) Perfect for a small shop where space is a premium, you can now effortlessly move around your Table and Band Saws, Planers, Jointers, and much more – this really increases your workspace, and allows you bring out the tool you need, and push it out of your way when done. All parts are included..