They look very similar to this one:
I still have some 200 mesh sieves available. If you are interested send me a PM or email. Since I got them very cheap I will only ask for there actual cost to me. (about ten pounds each)+posting from Holland (where I live)
Now regarding your question, i found this interesting link:
Mesh vs Micrometers vs Things we can relate to ;-)
Click in the menu on ''appendix'' and then ''conversions'' and you will find a lot of useful information.
Ciao,
Cloggie