This is a new and never-been-used Nikon MS-D70 battery holder that uses 3 CR-2 batteries. I found this in an old box and not sure how it got there. I haven't had a D70 for a very very long time. 

According to the Nikon USA website: The MS-D70 is a battery holder for CR-2 batteries, that is used to power the D70 or D70s D-SLR instead of using the supplied EN-EL3/EN-EL3a/EN-EL3e battery.

I don't believe that this would work with D200 or D300 models even though they used EL-EL3 variations. I think that they have different contact points inside the battery compartment.

Please look at the photos and email with any questions.