Professional and exquisite workmanship makes it very sturdy and hard. Sharp and durable feature makes it very efficient and reliable to use. Wear-resistant and rust-resistant feature makes it very practical and useful. The wide range of applications makes it suitable compatible many different materials. Made of high speed steel material, it is very durable to use. There are eight specifications compatible you to choose from: 3.0mm, 3.2mm, 3.5mm, 4.0mm, 4.2mm, 4.5mm, 5.0mm, 5.2mm. It is suitable compatible stainless steel, iron, aluminum alloy, plastic, wood and other materials and equipment such as hand drills and bench drills. Item Name: Double-ended Twist Drill Bit Material: High Speed Steel Features: Wear-resistant, Precision Punching, Different Specifications A: 3.0mm, B: 3.2mm, C: 3.5mm, D: 4.0mm, E: 4.2mm, F: 4.5mm, J: 5.0mm, H: 5.2mm Size Details: 3.0mm: Length: 4.4cm/1.73", Working Length: 1.1cm/0.43" (Approx.) 3.2mm: Length: 4.4cm/1.73", Working Length: 1.1cm/0.43" (Approx.) 3.5mm: Length: 4.8cm/1.89", Working Length: 1.4cm/0.55" (Approx.) 4.0mm: Length: 5.3cm/2.09", Working Length: 1.6cm/0.63" (Approx.) 4.2mm: Length: 5.5cm/2.17", Working Length: 1.7cm/0.67" (Approx.) 4.5mm: Length: 5.8cm/2.28", Working Length: 1.8cm/0.71" (Approx.) 5.0mm: Length: 6.2cm/2.44", Working Length: 2cm/0.79" (Approx.) 5.2mm: Length: 6.4cm/2.52", Working Length: 2.4cm/0.94" (Approx.) Notes: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 10 x Drill Bits