There are several functions of the stem extender

*Stem Extender Size: 0.9×0.9mm – 100pcs

• If you still have your original stem but it is broken and too short to use with your crown, you can buy a stem extender to lengthen the original broken watch stem to extend to the correct length that you need for your repair.
• If you have a pocket watch stem that has broken off and there is not a pocket watch stem available in a replacement, you can use a watch stem extender to lengthen the stem to fit into the pocket watch.
• You can use an extender that will change the tap (thread) size from a larger or smaller size to a standard tap (thread) size.