In part two of Ray Bradbury's novel Fahrenheit 451, titled "The Sieve and the Sand," former professor Faber and Montag have a very long conversation in Faber's house about Montag's desires to escape ignorance and the inability to think for himself. They discuss multiple ways to get citizens thinking again such as sabotaging the firemen program by planting books in firemen's houses, in order to make the whole system look corrupt, and printing their own books. At first Faber is far too scared of the dictatorial government to comply with scheming against the government. However, when Montag torments Faber's soul by tearing pages out of the Bible Montag has brought, Faber finally agrees to help Montag and shows him two objects, reproaching himself for having been too afraid to agree to working together earlier.
The two objects are tiny radio transmitters Faber has built and designed himself. The radio transmitters are "no larger than a .22 bullet," small enough to fit in a person's ear unseen by other people. Also, the devices not only allow the person wearing one to hear the person on the other end, they also allow the person on the other end to hear what's going on with respect to the wearer of the device. As Faber explains, "I can sit comfortably home, warming my frightened bones, and hear and analyze the firemen's world, find its weaknesses, without danger." Hence, Faber gives one device to Montag while keeping the other for himself. Since they both have radio transmitters, they can now be in constant contact with each other. In addition, Montag leaves the Bible with Faber.