Precision 1:21 gear ratio with sealed lubrication, cast housings, and metal knobs. Designed to fit modern 10mm headstock peg holes. Comfortable and simple adjustment of string tension. Trapezium-shaped button with sealed housing and a 90-degree fixing tag. Mounting hardware (screws, bushings, and washers) included. Guitar locking tuning machines with heavy-duty internal gear, robust and handy. Easy to install, simple to replace your old or dirty guitar tuning pegs. Please verify the parameter drawing in the attached pictures before placing your order