Wilmar W1399 12mm Serrated Wrench (12 pt.) Go to amazon.com Related posts Where to find serrated wrench? FeatureSize: 12mm12 point triple square.1/2" hex drive shaft.Heat treated alloy steel. Description12mm Serrated Wrench (12 pt.) Size: 12mm 12 point triple square. 1/2" hex drive shaft. Heat treated alloy steel.