8, 10 & 12mm bolts are for mounting the majority of cartridges on the market. The 16 & 20mm bolts are included for the deeper bodied cartridges and bolts (10mm & 16mm) are included for the majority of Thorens headshells. Contains everything needed to fit any phono cartridge. This selection of bolts, and washers cater for a full of cartridge body depths. Manufactured from high strength stainless steel not aluminium since many cartridge manufacturers specifically advise against the use of aluminium. Please that the cartridge is correctly fitted to the headshell making sure you for use the shortest bolts that will accommodate your cartridge / headshell combination. The socket for head on the bolts allows for easy tightening with the supplied allen keys., Manufacturer: Syanjin