Features19:1 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.DescriptionName: Left Handed Locking Tuning Keys Guitar Tuners Pegs Machine Heads BlackMaterial: Alloy Handle + A3 Steel Plate + Iron String Column + Copper GearColor: BlackPackage6 x Left Handed Locking Tuning Pegs6 x Ferrules6 x Screws