This Chicago-Latrobe HT18T TiN-coated drill bit and hand tap set contains 9 high-speed steel jobber length drill bits with a 118-degree conventional point and 9 high-speed steel plug-chamfer hand taps for use in general-purpose applications on ferrous and nonmetallic materials. Both drill bits and taps have a high-speed steel (HSS) construction that provides hardness for wear resistance, and the titanium nitride (TiN) coating withstands higher drilling speeds, increases drill bit hardness, and extends tool life when compared to uncoated tools.The drill bits are in wire gauge sizes #36, #29, #25, #21, and #7; letter sizes F and U; and inch sizes 5/16" and 27/64". A jobber length drill bit has a versatile midrange drilling depth that is a common choice for general-purpose drilling applications. The round shank accommodates most drill chucks.The hand taps are in thread sizes 6-32 UNC, 8-32 UNC, 10-24 UNC, 10-32 UNF, 1/4"-20 UNC, 5/16"-18 UNC, 3/8"-16 UNC, 7/16"-14 UNC, and 1/2"-13 UNC. These plug-chamfer hand taps have 3-5 threads that are reduced in height and produce thicker chips per tooth than taper-chamfer hand taps. They have a square-ended shank.The set comes in a gray epoxy-coated steel index case with labeled compartments for identification and organization. Case measures 7-3/8 x 4-1/4 x 1-1/4 inches (H x W x D). (H is height, the vertical distance from lowest to highest point; W is width, the horizontal distance from left to right; D is depth, the horizontal distance from front to back.)Drill bits are cutting tools used to make holes in a range of materials using machines such as handheld portable drills, machining centers, and lathes. Drill bits come in a variety of lengths and types, the most common of which is the twist drill bit. The round, twisted shaft of the twist drill bit typically has two cutting edges and flutes. The helical twist of the flutes brings chips up and away from the cutting edges and allows for coolant to reach the cutting edges. Jobber length twist drill bits, the most common length of twist drill bit, offer a good compromise of length and reach to work with the widest range of materials and applications. Mechanic's length twist drill bits (also called maintenance length) are a little shorter than jobber length and less prone to deflection when drilling. Short length twist drill bits (also called stub or screw-machine length) are the shortest and stiffest twist drill bits, helping to reduce the chance of deflection or breakage when drilling. Reduced shank drill bits (also called Silver and Deming drill bits) have a shank that is smaller in diameter than its shaft, permitting drilling machines with either a 1/2" or 3/4" drill chuck to create large holes. Long length twist drill bits (also called taper length) are a little longer than jobber length, allowing for deeper holes and longer reach. Extra long twist drill bits (also called extension) are longer than long length twist drill bits for greater reach or for drilling deeper holes.Chicago-Latrobe manufactures drill bits and accessories, reamers, countersinks, and blanks. The company, founded in 1890 and headquartered in Clemson, SC, meets International Organization for Standardization (ISO) standard 9001.What's in the Box?9 drill bits, wire gauge sizes #36, #29, #25, #21, and #7; letter sizes F and U; and inch sizes 5/16" and 27/64"9 hand taps, thread sizes 6-32 UNC, 8-32 UNC, 10-24 UNC, 10-32 UNF, 1/4"-20 UNC, 5/16"-18 UNC, 3/8"-16 UNC, 7/16"-14 UNC, and 1/2"-13 UNC Steel case