The Cleveland 3957-12, 12” extended shank, high-speed steel (HSS) drill bit has a 30-degree helix angle, with a 135-degree split-point and uncoated surface treatment, which helps optimize performance in general-purpose drilling applications. Conforms to NAS 907 Rev. 14 type A specifications. The shank diameter is the same as the drill size. This drill features an extended length shank for those applications requiring a long reach. The 3957-12 series performs best when drilling into various steels such as free-machining stainless steel, carbon steel, non-ferrous materials, and aluminum. With no coating or surface treatment, this uncoated tool can be used on a broad range of materials. Spiral flutes act as a passageway for chip extraction from the hole and for coolant to enter the hole. The twist of the flutes brings chips up and away from the cutting edge. 135-degree drill point reduces walking when starting a hole and penetrates more easily than a convention point. Round shanks allow use with a wide variety of tool holding systems. While the 3957-12 series was designed for the aircraft industry, it also works well in other industries. The extended shank provides longer reach than standard jobber-length drill bits. HSS is a common, general-purpose steel for cutting tools, offers toughness and shock resistance, and is compatible with a variety of materials. The tolerances for various aspects of the Cleveland drill bits are: drill diameter range through 1/8” +0.0000”/-0.0005”, over 1/8” to 1/4” +0.0000”/-0.0007”, over 1/4” through 1/2” +0.0000”/-0.0010”, over 1/2” to 1” +0.0000”/-0.0012”, over 1” to 2” +0.0000”/-0.0015”, over 2” to 3-1/2” +0.0000”/-0.0020”; drill overall length and flute length #80 through 1/8” +0.1250”/-0.0626”, over 1/8” to 1/2” +0.1250”/-0.1250”, over 1/2” to 1” +0.2500”/-0.1250”, over 1” to 2” +0.2500”/-0.2500”, over 2” to 3-1/2” +0.3750”/-0.3750”; drill point angle diameter range 1/16” to 1/2” included angle 118 or 135 degrees +/-5 degrees, over 1/2” to 1 1/2” included angle 118 degrees +/-3 degrees, over 1-1/2” to 3-1/2” includes angle 118 degrees +/- 2 degrees; drill lip height diameter range 1/16” to 1/8” total indicator variation 0.0020”, over 1/8” to 1/4” total indicator variation 0.0030”, over 1/4” to 1/2” total indicator variation 0.0040”, over 1/2” to 1” total indicator variation 0.0050”, over 1” to 3 1/2” total indicator variation 0.0060”. Drill bits are cutting tools used to make holes in a range of materials. They are used in machines such as handheld portable drills, drill presses, machining centers, and lathes. Drill bits come in a variety of types and lengths. Twist drill bits are the most common type of drill bit. They are a round, twisted shaft, end-cutting tool with two or more cutting edges and two or more flutes. Extra-long drill bits (also called extension) are twist bits with extended lengths for drilling deeper holes or greater reach. They are longer than long length bits. Greenfield Industries manufactures tools under the brand names Cleveland, Chicago-Latrobe, Cle-Line, Vermont Tap & Die, Bassett, Putnam Tools, Geometric, Vers-O-Tool, H & G, and Acme-Fette. The company owned by Top-Eastern Group and headquartered in Seneca, SC, makes tools that meet American National Standards Institute (ANSI), National Aerospace Standard (NAS), and Deutsches Institut für Normung (DIN) standards.