This 50 pack of 3/8" Cage Nuts are are zinc plated and designed for #12-24 screws. Cage Nuts are used to install rackmount equipment into server rack cabinets, 4-post racks, wallmount cabinets and racks, and 2-post racks. Cage nut style rails are often referred to as universal mounting rails, which are the most common type of rails used today.
If a rack or cabinet has cage nut style rails or universal mounting rails, they will require cage nuts. The thread size of the cage nut and the thread size of the screw must be the same to properly install rackmount components.