How to Measure Size

How to measure specific types of fasteners:

Bolts and Screws:
For all bolts and screws except countersunk screws, the length is measured from under the head. For countersunk bolts and screws, the length is the overall length (OAL).

Clevis Pins:
Measure length from beneath the head. This will be the length of the clevis pin as reflected in the Item Number.  For instance, CLP124 is a clevis pin, 1/2" diameter, 4" long (measured from beneath the head). The effective or usable length of the clevis pin is measured from beneath the head to the top of the hole.

Cotter Pins:
Measure length from beneath the head.

Flat Head Bolts:
Flat head bolts (also called countersunk bolts), are measured on the overall length of the bolt.

Hex Head Bolts:
Hex head bolts are measured from under the head to the end of the shank.

O-Rings: 
For information on O-Ring sizes, please see our O-Ring Size Reference.

Safety Pins:
Order using the diameter and overall length (OAL) and industry #. May be beneficial to call our Help Desk during normal business hours.

Socket Shoulder Screws:
Order by the diameter and length of the shaft. The thread size defaults automatically to the next smallest diameter.

U-Bolts:
Order using the pipe size the u-bolt will be used to hold.

May be beneficial to call our Help Desk during normal business hours.