I stock those mask at my office and usually have 100+/- on hand always. I was questioned by my HQ with some other office how many I had and they asked all of us to ship them to the HQ warehouse.
Hummmm
Sorry to say I only had 2 on hand when they sent the request
I just renewed our normal order and it will be 3 months before the order is filled.
Guess you had better buy them when you can find them......