Another form of closed communication used in the books and films is a set of mirrors which belonged to Sirius Black. Sirius gives Harry one mirror in "Harry Potter and the Order of the Phoenix", with a note explaining to Harry that Sirius and James Potter used to use the mirrors to talk to each other when they were put in separate detentions. In "Harry Potter and the Deathly Hallows", Harry uses a shard of his broken mirror to call for help from the Malfoy's cellar, and later finds out that Aberforth Dumbledore had been watching over Harry using Sirius' mirror, which he obtained from Mundungus Fletcher.