Needs as little as 5 degrees to move a fastener. 180 degree flex action head that allows access into the tightest applications. Short pattern along with the slim head and body allow the stubby wrenches into places where no other wrench will work. Enhanced open end design with Surface Drive Plus Technology that prevents fastener rounding. Size stamped on both sides for ease in identification Sizes include: 10mm, 11mm, 12mm, 13mm, 14mm, 15mm, 16mm, 17mm, 18mm and 19mm.