Swiss made, alloy(silver color), vintage, new old stock mainsprings, multiple sizes arranged by dimensions. 166 types to choose from. I am adding more as time goes by so if you don't see the size you need now either ask me or come back at a later date and see if I have added the spring you need. Please note there is one "blue steel" spring in this listing and I have noted that in the pic of the spring. Swiss part number for these springs is 770(manual wind watch mainspring) Sorted by height, strength, and then length in MM. Also note in the pics the MM diameter of the spring in the installation ring. Your inner barrel diameter will need to be at least that large to accommodate the spring length. If you have a question, ask. Select the spring you need from the drop down list above.All mainsprings in this listing are for manual wind watches.See my other listing for springs for auto-wind watches.You get one spring per order.Ask questions before you order. Thank you for looking!