What’s to go wrong with it?

My eclipse viewer, I noticed after viewing the course of this morning’s partial solar eclipse, carries a warning not to use it after August 12th 1999.
    Good job they didn’t make it instantly visible or I might have started panicking. And as it lives in a drawer when not in use, which is hardly ever, how am I going to wear it out?
    p.s. At least we got to see this one.