‎9 Piece = 4 mm and 5 mm Bit have 5/16″ Hex Drive–6 mm, 8 mm, 10 mm and 12 mm Bit have 1/2″ Hex Drive–14 mm and 16 mm Bit have 5/8″ Hex Drive–18 mm Bit has a 3/4″ Hex Drive–12 Point - Triple Square Bit Set