Features 19:1 Tuning Ratio. Fits for 10mm Hole. Fine sealed machine heads. Excellent and the finish is flawless. Just slip the String through the hole, tighten the Locking Thumb Wheel, and Tune the String. Description Name: Left Handed Locking Tuning Keys Guitar Tuners Pegs Machine Heads Black Material: Alloy Handle + A3 Steel Plate + Iron String Column + Copper Gear Color: Black Package 6 x Left Handed Locking Tuning Pegs 6 x Ferrules 6 x Screws