The dimensions of a bolt can be expressed in metric or imperial units, both of which are better explained in the Bolt Standards section of this selection guide.

These screws are available in metric and imperial units ... as well as a drive mechanism (slotted, hex, etc.) so the screw can have torque applied for its installation. The shoulder is the smooth, ...

metric hex, metric socket, and metric square head bolts and nuts. Its products are used in various applications, such as automotive, plumbing/valve assemblies, aerospace, marine/military ...