Plastic Fire Hose Cap and Chain 1-1/2" NST Anti Theft FDC Cap Red plastic cap with National Standard Threads (the most common). Includes Cap & Chain Fits some standpipe systems and connections. Provides protection against foreign material into the FDC threads. Quick access when fire hose connections are needed. Durable plastic meets code and detours theft of fire department connection caps. Threads are on the inside of the cap and not on the outside