Abstract: Identification device for distinctively marking objects, location or sides of symmetrical objects such as audio tape cassettes, so that they can be distinguished in the dark. A carrier lamina has a matt phosphorescent pigment coating exposed on one side so that indelible writing or other marks can be made thereon using a writing instrument. The dark writing or other marks are viewable in the dark in contrast against the glow of the unmarked phosphorescent pigment surface and will not smudge or erase when handled. The opposite side carries a permanently tacky pressure sensitive adhesive coating so that the phosphorescent lamina can be easily adhered on objects or locations to be marked.