This steel filler neck is most often used in older formula car fuel cells. It is typically installed into a molded neck in the bladder and held in place with hose clamps. The 2 1/4" OD neck accepts a 2 1/4" Quarter-Turn Non-Vented Filler Cap (Part No. 2518, sold separately). No provision for breather outlet. Approximately 2 3/4" high.