The Doctor’s multipurpose tool is a Gallifreyan device with numerous settings, which is easily controlled at the press of his thumb. The Doctor has had many sonic screwdrivers of different designs throughout his life. The sonic screwdriver is a fictional tool in the British sci-fi television series Doctor Who. Its most common function is to operate virtually any lock, mechanical or electronic, and thus open doors for escape or exploration. It has also been used for repairing equipment, as an offensive weapon, and occasionally even to drive screws. Like the TARDIS, it has become one of the icons of the program and is closely associated with the Doctor.