For Hand Tapping Only * Each set contains two 5" long extensions, which can be used either alone (to lengthen the tap 5")or in combination (to lengthen the tap 10") * Extensions are considerably less costly than special length taps and can be used again and again * Made of carefully heat-treated alloy steel for strength and durability * Resistant to wear and can be used again and again, unlike the taps that go into them