Ordinary twist drills are readily available. Really good ones are much harder to find. These are made of high-speed steel (will stay sharp much longer) and are extra-long, full jobber sized. Designed to be used in a drill press or an electric hand drill, they are superb for use in all hardwoods and metals, except hardened steel.
Each set comes racked in a metal case for easy selection. The 13-piece set is 1/16" to 1/4" by 64ths. The 15-piece set is 1/16" to 1/2" by 32nds. The 29-piece set is 1/16" to 1/2" by 64ths. Number sets are also available. Bits up to 3/8" are shanked to size; larger bits have 3/8" shanks.