Cast Iron Surface Marking Gauge 9" -12" Block Adjustable Knob and Hardened Scriber Consists of Adjustable Knob and Hardened Scriber. Round base made of close Grain Cast Iron. Very Useful for every Workshop. Surface Marking Gauge 12" Excellent surface marking gauge with fully ground base, which serves as an accurate reference surface. Adjustable shaft with a scriber which can be locked in any position along the shaft. Can be used on flat or round surfaces. Features fine adjustment and hardened scriber points Supplied 12" , 300mm