Developed for areas where FDC caps disappear frequently, the Knox FDC CapTM secures the connection. Fire departments can depend on clean access to fire sprinkler systems in school buildings, industrial structures, and in downtown commercial areas–anywhere cap removal and junk in the lines is a problem. Secured with a Knox KeywrenchTM, the cap is easily and quickly removed during an emergency. The Knox FDC Cap 2 1/ 2 inch male plug has three types of threads available: National Standard, New York Corp, and Pittsburgh. Other thread type requests are welcome.