A power driven drill bit and an extractor in one tool. Use with a 3/8" variable speed reversible power drill to extract broken, rusted or stubborn bolts. No grinding or center punch required. Self centering tips work on jagged, uneven breaks. Four piece kit includes 1/4" (M6), 5/16" (M8), 3/8" (M10) and 1/2" (M12) bits.