Grover model 870BR rosewood button Champion Sta-Tite Patent Series tuning machines fits most tenor banjos, dulcimers, and ukes without modification. The metal shank and two knurled bushings press tightly into a 5/16" headpiece hole on headstocks from 7/16" to 5/8" thick. Patent #206,460 for special retainer design. Features Grover's lifetime guarantee.