This is a crown style, chrome replacement button set of 6 for Grover Rotomatics (102 Series) and more. Similar style to what is on my 1970 Guild acoustic and what was used on some Gibsons over the years. Many tuners for guitar, ukulele, banjo, mandolin, and dulcimer have buttons on their tuners that can be replaced. Replace a worn, pitted or discolored button or replace the whole set to give your instrument a new or unique look. These are also sold individually in my other listings. These measure 3/4 inch in length, 3/4 high, and 1/4 inch thick at its middle. The screw hole is 7/64 inch diameter. The shaft diameter is 9/64 inch. These are interchangeable on Grover Series 102 (Original Rotomatics), 106 (Locking Rotomatics), 109 (Super Rotomatics), 150 (Imperial), and possibly 205 (Mini Rotomatics), 406 (Mini Locking Rotomatics) if spacing permits.