For use on brake, A/C, fuel and power steering lines, the S.U.R. & R. LW750 Ratcheting Flex Head Wrench Set is backed by a lifetime warranty. As more pressure is applied to the wrench, the grip on the nut tightens. Made from hardened, tempered chrome vandium steel. This Deluxe Metric Set includes the following sizes: 8mm/9mm, 10mm/11mm, 12mm/13mm, 14mm/15mm, 16mm/17mm and 18mm/19mm.