Great High Quality BNC female to female couplers/barrels. Gold Plate internal socket pins. Useful when you'd like to join two male BNC cables together or making an extension. Works with all known 75 ohm and 50 ohm male plugs such as composite video, component video, ham radio. Well-made and all metal. Warranty: As described and fully functional.
Features
• Couples devices with male BNC interfaces
• Cost effective and reliable device
• Reduces signal loss and allow error-free data transfer
• Suitable for extending cable runs with male BNC connectors
• Effective in solving your interconnection problems
• Ultimate combination for routing cables
• Improves cable management of the unit
• Eliminates impedance mismatching and distortion
• Provides mechanical durability
• Coupling allows for quick installation
• Prevent thermal shocks and flammability
• Moisture, corrosion and vibration resistant
• Provides a strong mechanical and electrical connection
Coupler does couple ! 
Excellent product.