Top quality Wilkinson bass guitar machine heads, ultra smooth action, with full size base plates. Vintage style buttons. These are excellent quality machine heads from Wilkinson. 1. Please note these DO NOT fit most modern standard USA/Mexican Fender P/J Bass, or Squier or import bass models as they have the 70s large backplate. Please be sure to verify the dimensions before ordering 2. 20:1 Tuning Ratio; Direct replacement for 60 or 70's Vintage P and J basses; ultra smooth action with full size base plates 3. Requires 11/16"(18mm) peghead holes. Mounting hole spacing is 1-5/16" across the top, 1" across the bottom, and 1-7/16" top to bottom(on center). Reversible for right or left hand use. Includes bushings and mounting screws. 4. Quality is Excellent and the finish is flawless 5. Package includes Bass Tuners x 4 Assembly tip: do not drill any holes until you've checked the spacing of all the turners together. The back flanges literally butt up against each other. I'll try to post some images later.