Genuine Fender Pearloid Tuning Button for Banjo tuning machines - Single Pearloid tuning button for Fender Banjos 5th string tuning button and has been used for the 4 string tuners Bottom insert is 5.21 x 4.17mm, Top outer insert is 6.5mm steps to 3.46mm Part Number: 0057581000 Available at Ant Hill Music!