SK Hand Tools 89301 5 Piece Metric Spline G-Pro Wrench Topper Set 20mm, 21mm, 22mm, 23mm, 24mm Spline G-Pro Wrenches. Packaged in a blow molded case. Works on various types of fasterners, spline, 6 point, 12 point, 50% rounded, torx and square 90 teeth design delivers 4 degree effective swing arc. Non-slip feature on the open end can be used on damaged fasteners that are up to 70% rounded. Packaged in a molded plastic case