Assortment contains 2-piece each of: 1/4 x 3/8 in, 1/4 x 1/2 in, 5/16 x 3/8 in, 5/16 x 1/2 in, 3/8 x 1/2 in, 1/2 x 5/8 in, 1/2 x 3/4 in and 5/8 x 3/4 in. High quality steel material. Zinc plated finish. Sizes are 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. Precision Brand® Keystock Assortment, Rectangle, 16 Piece, 12 in L, Steel, Zinc Plated