Small Jaw Crusher 2 1/4″ x 3″. The discharge opening (closedsidesetting) of this 55 mm X 75 mm "bigsmall crusher" you can adjusted with a wrench. With a short throw at a quick 525 RPM (speed eccentric overhead), this small rock crusher can almost pulverize without dusting of your runofthemill, chain beating, hammermill small prospectors often buy.