The Spoke Gauge and Length Ruler is made out of stainless steel. It measures spokes up to 14 inches (top edge) or 350 mm (bottom edge). It can also be used to measure 1.5, 1.6, 1.7, 1.8, 2.0, 2.3, 2.6, 3, 2.5, and 4 mm gauge spokes/wire. (Part#: SMASR0)