Looking for an original battery cover (the one that has the threads to mount the angle of view reducer) for the Nikon Photomic finder (the external direct reading model). Mine came with a common/replacement cover, and well, you can't store the reducer that way.
After doing some research, I found out that my finder is the original version, thus it came with the plain battery cap. No need to change it, as I'm not using the finder anyway. Consider this post closed.