The light bulb is made by the German manufacturer of speciality lamps Dr. Fischer and is equal to the Philips Photocrescenta lamps which is no longer made by Philips.
The Photocrescenta lamps are especially made for use with B&W photo enlargers. They have an internal white coating, which emits diffused, very uniform light at high luminous output. Max. permissible base temperature is 250 °C. The burning position of Photocrescenta lamps is universal.