Transparent HiRes plastic goniometer permits observation of joint's axis of motion, and its range of motion. The HiRes design ads a white line behind measurement gradations to make the readings easy to see. The 360° head has three scales calibrated to be used with the ISOM (International Standards of Measurement, STFR) system. Arm has a linear scale in inches and centimeters and remains at measurement position until reset. Angle scale reads 1° increments. Rulongmeter Style - HiRes 360 Degree Head - 7 inch Arms, 25-pack