I bought this off a friend a few years back and never got a chance to use it. It is a EO-Tech holosight: model 521.L80. Takes 2 size N batteries. Red Circle-dot holographic reticle. Clamps to standard rails. Good condition. Asking $300 obo plus shipping from Michigan. PM if interested and I can email photos.
I was right! I thought it was from a bow sight as it didn't have a slot in the screw for the elevations adjustment. I have two of these I got used from a bow shop a couple years ago.