INGS-INTERNATIONAL NUMISMATIC GRADING SERVICE
I don't think they're in business anymore so the address on the slab may not be accurate.
International graded coins in the mid to late 80’s. The back of every normal production slab has a copyright date of 1987 and their slab is nearly identical to the more recent Global service and even has the hands holding a globe that Global uses today.
Compare your graded coins to our grading guide's photographs.