Gotoh Relic Series SD91 Tuning Keys Aged Nickel Set of 6 in Line Gotoh SD91 Relic Series Tuning Keys. Perfect for replacing worn or old tuners on Vintage guitars, or easily adding that aged look to your relic or custom project. Includes Bushings and fixing screws. 1:15 Ratio. Requires 8.75mm diameter (11/32") hole.