I see that some people here have lots of knowledge on watches, and I need some help.

My IWC Cal 52 watch needs a new mainspring and I haven't been able to find one.

Any idea of where could I get one or a similar one that might work?

Maybe the size of it so I can get a similar one that my watch maker can set in the movement.

Any feedback will be highly appreciated !!

Thanks for your time.