* Made from highly polished chrome vanadium steel with 1/2" drive. * Sizes: 1/2" Drive 21mm Spanner or Ratchet 6mm, 8mm, 10mm and 12mm * Hex ends allow use with 21mm spanner. * These stud extractors are the concentric roller bearing type that won't damage the thread on the stud. * Integrated concentric roller bearings stud extractors.