Do you know the exact OD and thickness that you need?
21mm x 2mm
Thanks for the info !
I haven't really searched in detail, but Otto Frei appears to have 21mm x 0.9mm available (though I didn't notice any thicker crystals in the smaller OD sizes) ... not sure how much of an issue that might be - :shrug:
EDIT - Jules Borel may be another source ... looks like they might be able to do 21.0mm x 2.0mm (if I am reading their catalog correctly?) -