These nicely made nickel plated steel screws are the most common size you'll find out there. They fit every vintage Kluson style bass tuner I know of exactly. They also fit the '70s Fender bass tuners and all of the Gotoh vIntage Kluson style bass tuners you'll find on the reissues. I measured exactly 2.5mm on the main threaded portion of the shank. Length of threads is around 10mm. Head diameter around 4.38mm. A set or two is a must for your roadie kit of parts. Please note that the Wilkinson tuner is not included in this sale. It is shown so folks can see what kind of bass tuning machine these screws are for.