From the "manual" that came with my new Vevor 4" mill vise. The actual vise is pretty nice, especially considering that it's 1/10th or less the price of a Kurt. BTW, it's advertised on Amazon as a "Happybuy" and a few bucks cheaper than the one listed as a Vevor. Came in a Vevor box. Of course, Vevor is a re-seller, not a manufacturer, so that didn't come as much of a surprise.