The tip of my old soldering iron was too big to work with tiny SMD (Surface Mount Device) parts. I asked a foreman at an assembly shop that makes 1,000 SMD electronic boards a month and he told me that his team really likes the Edsyn 951SX. After more than a year of use, I understand why. The tips are much narrower than my old Weller piston, making it relatively easy to solder individual SMD pins with a 0.025" centering. The temperature control feature is useful when soldering large and small leads/pads with different types of solder, but it Some experimentation is required to get the best result Edsyn offers a wide range of interchangeable ear tips for this model, which can be changed and heated quickly.