This is an antique yellow filter used to enhance contrast of black & white film. The imprint on the cover of the box has worn off but if you are familiar with vintage logos you can probably decipher it.

The filter itself has a brass ring and was meant to be used as a cap over the camera lens. There are no markings on the ring.

The storage box is not in good shape. Two sides of the cover are damaged and the glue used to fasten the velour and silk liners to the box has dried out.

This is a nice item for antique large-format camera collectors