I need replacement soldering tips 1.6D for a 937 soldering station. You list a 918-T-1.6D and 920-T-1.6D. What do I need for the 937 station?

The 937 and 936 soldering stations can be used with three different soldering irons. The particular soldering iron determines the tip series. If the iron model number is 900S-ESD the tip series starts with 900S-T-xxx. The 907 model soldering iron uses 900M-T-xxx series tips and the 908 model iron uses 900L-T-xxx series tips. The most common soldering iron is the 907 model.

900S - Small 

900M - Medium 

900L - Large