1/2” DRIVE, NUTTWISTER  The NUTTWISTER's six teeth have a special helical structure that tapers inward, locking onto the rounded-off bolt or nut for removal. The NUTTWISTER can be applied to any round bolts like stud bolts, cap bolts, provided the correct size is used and the bolt or nut is unbroken.  Input Drive Size: 1/2 Sq. Dr. Nut Twister 19mm Length 120mm