This is a 6-piece set of plastic goniometers that includes 1 each 12", 8" and 6" 360 degree goniometers; 1 each pocket 180 degree goniometer, 360 degree rulongmeter and finger flexion/hyper-extension goniometer. These transparent plastic goniometers permit observation of a joint's axis of motion and its range of motion. The primary purpose of these devices is to assist in physical therapy by determining range of motion of a joint as well as evaluating and gauging recovery after surgery or physical therapy. The heads have three scales calibrated to be used with the ISOM (International Standards of Measurement, STFR) system. These are essential tools for treatment, rehab and surgical recovery and evaluation. Suitable for home use as well as multi-user environments. These goniometers let you measure joint limits and range-of-motion as well as hyperextension through flexion. The arms have a linear scale in both inches and centimeters. They also will remain at the last measurement position until reset. The angle scale reads 1 degree increments. The clear plastic of the goniometer allows the device to be placed directly and exactly on a joint or limb for easy observation. These Goniometers are Baseline products, which means it?s a trusted name in measurement and evaluation instruments. Baseline products have been used by Medical Professionals, Therapists, Doctors and Rehab Clinics all over the world since 1974. If you have ever received therapy after an injury, you have probably had your progress tested and measured with a Baseline measurement instrument.