Manufactured from high quality alloy steel. Includes a taper, plug and bottom tap in each size. Supplied in a steel storage case. PROFESSIONAL QUALITY - Manufactured from high quality alloy steel. VERSATILE USE - Includes a taper, plug and bottom tap in each size. CONVENIENT STORAGE - Supplied in a steel storage case. COMPREHENSIVE METRIC SIZES 21pc set includes: 3 x 0.5, 4 x 0.7, 5 x 0.8, 6 x 1, 8 x 1.25, 10 x 1.5, 12 x 1.75mm (1 x Plug, 1 x Taper, 1 x Bottom Tap of each).