Don't let your iron run for hours and hours if you're not using it. It can cause the tip to get black oxide coverage These tips are made of oxygen-free copper, easy to tin and diamagnetic, suitable for low temperature soldering These soldering tips are suitable for soldering stations 936, 937, 938, 969, 8586, 852D Try tinning the tip as it heats up. If you leave it on for too long or heat it too hot, it will burn the solder and turn black There are total 10 kinds of soldering tips in this set, and you can choose the one that suits different needs of your welding. Copper soldering tips are suitable for low temperature soldering. There are 10 types of soldering tips in this set and you can choose the right one for different soldering needs, for example, shape b type versatile which can be used in any direction and easy to hold in any direction. position, possible to weld any surface from small to large and shape Type k is knife-shaped and capable of soldering by applying the tip in 3 ways: line, face and point, it is used for narrow pitch soldering, bridge correction and drag soldering. Get this set of tips and make your soldering job easier. Features: Try tinning the tip while it's heating up. If you leave it on too long or run it too hot, it will burn off the solder and turn black. These soldering tips are suitable for 936, 937, 938, 969, 8586, 852D soldering stations. Features: Material: oxygen-free copper Surface finish: electroplating (nickel iron) Length: approx. 42mm or 1.65" Outer Diameter: 6mm or 0.23" Inner Diameter: 4mm or 0.15" Temperature range: 200 - 480 Form: I, SI, B, K