The most responsive soldering iron available. Uses tip-heater cartridges, supplied separately. The Instant SetBack Cubby automatically puts the system (ST 30, ST 50, ST 65, ST 70, ST 75 and ST 115) into SetBack mode when the TD-100 Iron has been in the cubby for 45 seconds. SetBack mode means that the temperature is set to just below solder melt temperature so the corrosive action of the leaded or Lead Free solder is stopped, maximizing the life of your tips! The system reverts to normal operation when the iron is removed from the cubby.