Exceptionally smooth tuning — Our Golden Age Classical Guitar Tuners are high quality tuning machines for nylon-string classical guitars. The elegant Landstorfer "fish scale" pattern recalls styles used by master luthiers Velazquez and Hauser. 15:1 gear ratio for improved tuning Brass baseplates in relic patina Removable ebony knobs 3/8" (9.86mm) diameter string roller sleeves are durable white plastic 1-3/8" (35mm) string post spacing Each set includes a pair of 3-left/3-right tuning machines with mounting screws. Installation Tips Peghole spacing: Plate-mounted tuners can't work efficiently if the pegholes are improperly aligned. Our Tuning Machine Drill Jig for Slotted Pegheads (sold separately) ensures the correct 1-3/8" string roller spacing for accurate tuning. Mounting screws: Pilot holes required. Installing delicate screws into hard wood requires great care and accuracy. We highly recommend a 5/64" drill bit for the pilot hole before installing these screws. Lubricate the screw threads with cutting lubricant (also wax or a bar of soap) to reduce friction and help them thread properly.