Description
The nut fits a standard bolt that has a diameter of 3/8″ UNC approx: 9.53mm.
It is therefore an American coarse threaded bolt that has an outer diameter of 9.53mm, which is then called 3/8″. It has 16 threads in one inch = 25.4mm, if you are unsure, you can count the number of threads the bolt has in 25.4mm.