Good working condition. Residual Current Device tester plug (RCD). For added protection against electric shock and to instantly cut the power in the event of an earth connection leakage, use this efficient and child resistant Masterplug RCD 1 socket adapter. Single socket. 13 amp. Plug socket. Use to instantly cut the power in the event of an earth connection leakage. For indoor use. Child resistant sockets. Non-latching type (when power is cut to the device, the RCD will trip and have to be reset). Other timers available, and lots of other items too, see "Seller's Other Items". Many thanks for looking! Daniel 😀