This is a set (6 on a side) of genuine Grover Mini Rotomatic(R) tuners in chrome, part number 205C12, new and blister packed. Gear ratio is 14:1 with precision cut worm and gear for perfect meshing, eliminating backlash and slippage. Gearbox is permanently lubricated and countersunk tension screw permits the player to regulate the tuning tension to custom feel. Mini buttons allow more space for your fingers for tuning your strings. Post hole size is 25/64". 5/8" washers, bushings and screws are included. They are a perfect replacement for your existing tuners. All necessary hardware and screws are included. Upgrade that 12 string guitar with some new hardware today! No modifications necessary for most guitars. Please check the size of your existing post holes. Take off the old ones, put in the new. These come with a lifetime factory guarantee. Return to Grover for a free repair or replacement.