Weller 537S 23W Heater Element for Thread-On Tip Use with standard series modular iron handles 7400, 7500, 7760 and 7770 Interchangeable standard Line heaters for modular series handles and tips Standard Line heaters from 23 to 50 watts Available Temperature range varies from 700 F to 1100 F Based on heater wattage Modular heaters are Available in thread-on, thread-in and integral tip designs