Plug

'''Plugs, or more specifically, electrical plugs, were an obsession for Arthur Weasley. To the dismay of some of his family and friends, and the amusement of others, he collected them, read about them and tried to understand how they work.

For readers in the US, it may help to understand this fascination, if you know that electrical plugs and sockets are not as standardized in the UK. So appliances may be sold without the plug; plugs are purchased separately and attached to match the socket in the muggle's home.