This is an ALTAIR LIGHT SCREEN. It has been stored on a shelf for a long time and has some dirt. It appears to be a light screen that, when set on the pin and glass of a twin-lens reflex camera, increases the brightness tenfold. The box is printed with No. 4, so it is likely for a Mamiya camera. I cannot guarantee the specifics, so please check the included instructions. As it is an old item from the Showa era, there may be other unnoticed issues. Please refrain from purchasing if you are concerned.