How Fastener Measurements are Notated

Drive Type

Drive type describes the type of tool used to install the fastener. Common examples are phillips, slotted, and square drives.

Some fasteners, such as carriage bolts, do not have a drive and therefore no drive type is specified.

In certain other cases, such as with hex bolts, the head and drive type (hexagonal) is implied by the fastener type.

Head Style

Head style describes the shape of the head. Common examples are pan, flat, truss, and hex.

A few fastener types, including set screws and some anchors, do not have a head and the head property will therefore not be present.

Plating

Many fasteners, especially steel fasteners, are plated or coated for corrosion resistance or decorative purposes. Common platings include zinc plating, galvanizing, and chrome plating.

Grade

Some materials, such as steel, come in various grades. The grade specifies an exact set of mechanical properties. Examples of common steel grades include grade 2, grade 8, and class 8.8.

Material

This is the basic underlying material. The most common fastener material is steel (including stainless steels), often further specified with a grade (grade 8, etc.). However, many other materials are used including, brass, bronze, and nylon.

This property will always be present even if no grade or plating is specified. Thus, a full material description for a fastener might simply be: Brass.

Other Information

Occasionally the material description will contain other information. Examples include fasteners with painted heads, colored platings such as yellow zinc, or polished finishes.

For more information on materials see our Materials page.