Like in the description, I am now a one shop place for Dueber Hampden parts.   These  16 size mainsprings.  There is one problem, no T on the end.  These came direct from the factory.  My 95 year  old watchmaker friend has had them since 1946.  If you have the skills you can remove the old T end from your old mainspring and re-rivot the T end onto these, I have done it and you can do it in a few minutes and save a bunch of money.  I revised this to six because I wanted it to come in original package from the factory. I have thousands of these and I am sharings my good fortune with you,  You are getting 6 mainsprings direct from the factory,  As a side note these will work with most 16 size watches that use a T end or you could attach whatever end comes off your worn out mainspring. Check with a company called Casker for their mainspring chart.  I have used these in a South Bend so far and will try others. Shipping $4 now matter how many you buy.