High quality steel material. Zinc plated finish. Size is clearly marked on each piece. Precision Brand® Keystock is used to provide driving torque between shafts and pulleys, gears, sprockets, etc. Used for new machinery, general maintenance, and shop repairs. It is a necessity in all applications where rotating power devices are used. Most tolerances on dimensions are oversized to assure tight fits in keyways for positive, zero backlash power transmission.