I've looked through ebay, manuals, etc. and am not able to find an image/explanation for this Rolleiflex accessory. The camera was purchased at an estate sale. I also purchased a Weston light meter. The accessory is pictured in the upper right hand corner of the photo, it has an "HR" emblem on the front. It also came with an electric cord that affixes to the front, pictured in the second photo.