Extra-long "aircraft length" drill bits offer superior access and versatility * High speed tool steel for greater heat resistance and faster cutting speed * Set of five 12" bits in most-used sizes: 1/8"(3mm), 3/16"(5mm), 1/4"(6.5mm), 5/16"(8mm) & 3/8"(10mm) * Fluted design helps expel cut material for more-efficient drilling & extended bit life * Use on steel, aluminum & other metals, hardwood, plastic & fiberglass