USCamera Canon A-1 mirror cage light baffle.  This baffle sheet is on the inside of the mirror box on the left side. The anti-reflective sheet Canon used had a tendency to curl as it ages.  This replacement part from USCamera is a special type of poly-urethane material that was used in many film cameras produced in the 1980's and later. Just a couple camera models where I can see this baffle material was used is Nikon N2000, N2020, and later used in the Minolta XE-7 as an updated replacement part. Black adhesive tape has already been applied so to install just, peel material from the backing to apply. I strongly recommend an adhesive delay so you have time to align the baffle in place. Material made in Japan for USCamera.