Hi Martin, you got me thinking there, I had two of them but since got rid, not because they were no good but I was intending to try some others out. I did the same with night vision, I like to experiment with gadgets.
I will try and look them up and get back to you Martin. They were the cheaper ones around £80 each if my memory serves me. I used to but external 12 volt batt on them and they lasted for ages unless the badgers pulled the wires out. The battery went up the tree after that.
FM