This Standard covers general and dimensional data pertinent to the various types of screw and captive washer assemblies, otherwise known as sems, which are recognized as an American National Standard. (The word sems is a generic term applicable to screw and washer assemblies.)

The inclusion of dimensional data in this Standard is not intended to imply that all of the products described herein are stock production items. Consumers should consult with respective suppliers concerning the availability of products.