Keson MP315M Metal Frame Measuring Wheel with Solid Plastic Wheel (Graduations: M, DM), 0.318-Meter Diameter Innovative design for simple, center-line functionality and great balance Huge numbers make for easy reading The metal shelf keeps dirt and debris from coming into contact with the critical counter Rugged 3/4 inch steel frame, tough enough to handle any terrain Easily reduces to 1/2 it's size for storage and portability