Unibit®: Step Drill Bits are the moste recoognized brand for professionals in electrical, automotive and plumbing. UNIBIT fulfills the IRWIN tradition of providing reliable, high-quality professional tools. IRWIN UNIBIT has been teh most innovative and trusted name in step drill bits since its invention in 1972. The new IRWIN UNIBIT Cobalt is the latest addition to the step drill bit category. Made of cobalt high speed steel, this step drill bit will last longer in the toughest of materials. From stainless steel to aluminum for PVC pipe, the UNIBIT Cobalt is the most versatile and longest lasting step drill bit in the market.