There are two ways to select the correct mainspring for your watch movement.

What you need is the "Catalogue of sizes of referred watch mainsprings" by Uniressor, for both ways of search. The mainsprings come in a package of 6.

• In the book mentioned above (each watchmaker has one) you can look up the caliber of your watch. For example; you are looking for a mainspring for Omega caliber 30 SR. In the yellow part of the book you search for Omega and then on 30 SR. Here you see that you need a mainspring with number 150-26. The number 150-26 can be looked up in the list of references and standard sizes, so you know what sizes and references the mainspring should have. For example; 150-26 has the sizes 1.50 x 11 / 11.5 -0.14. (spec.: Hight 1.50 mm, 11/11.5 mm barrel width -diameter, 0,14 mm thickness)
• The green part of the book tells us what mainsprings can be used of different calibers by different watches. The 150-26 for example is also used in some Ebel, Lanco, Roamer, Tissot and Valjoux movements.

remark: The table of references and standard sizes (the white pages of the catalogue) ; the heights close to certain marks have been grouped to facilitate interchangability (1.20 with 1.15, 1.35 with 1.30 or 1.15 with 1.20 and 1.25 with 1.30. The diameter is rounded of to the nearest 0.5 mm.

We can help you on your search, please email us with the brand name of the watch and the caliber of the movement.

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