Special locking design to remove any size nut between 9 & 21mm. Pin Size: approx. 2.9mm (Hex); external diameter: 27.8mm; pins retract approx. 10.2mm. For use removing damaged nuts & bolts, including Ribe, Spline, Hex, Square, Triangular or Star. Ideal glove box tool. Manufactured from chrome vanadium. Not suitable for impact tools.