This free-spinning wheel marking gauge from iGaging allows you to make precise hairline layout marks both with and across the wood grain. A beveled edge hardened steel cutting wheel scribes a fine line without tearing wood fibers. The bevel angle also creates a natural pull that helps keep the gauge against your workpiece for straight marks. The precision machined solid-brass body quickly locks into position on an 8-inch steel rod shaft with the turn of a knurled knob. The shaft beam is graduated in 1mm and 1/32nd-inch increments for easy reference, which also allows it to be used as a quick measurement depth gauge.