This extremely popular unit has revolutionised experiments because of the quality of the traces it makes, and the reliability of the mechanism ensures that ticker-tape experiments are no longer hit and miss.There is no double-dotting or smearing, even at high speeds. No pen or carbon discs are required. Friction between tape and ticker-timer is kept to a minimum.Excellent results can be expected.The unit comes with a boss-head so that it can be easily clamped in a rod.Requires 2 - 4V AC from a low-voltage power supply (not included).The unit is protected by a 2A internal fuse. A Power Supply with a voltage limiting lock is preferred (PP00057619)The Timer uses self-marking paper tape which is included.Replacement Tape can be supplied separately: B8R07098