This SAE Recommended Practice was developed primarily for passenger car and truck applications but it may be used in marine, industrial, and similar applications.The purpose of this document is to provide dimensions for two types of threaded fuel tank filler caps (pressure/vacuum and nonvented or vacuum only) and the corresponding cap retainers. The use of these dimensions prevent the use of a nonvented or vacuum only cap with a pressure/vacuum cap retainer. However, these dimensions will allow a pressure/vacuum cap to be used on a nonvented or vacuum only cap retainer.