The #620 Exposure meter was made by Metrawatt in Germany. Each meter carried a unique serial number over the metering cell. The unit's life spanned the transition for LV to EV numbers — so rings for both systems were included with the meter, which could be changed by means of two small screws and the supplied 'teardrop' screwdriver. The setting for use with the #621 Booster is marked on both rings.

The other item (left) is an alternative accessory clip and screws so the meter can be used with older cameras having the smaller Polaroid shoe