This is a SONY head eraser (head demagnetizer) HE-2. It's what's generally called a head demagnetizer. The code says "1973," so could it be over 50 years old? I don't have an open reel deck, and even if I did, I wouldn't know if it was working. However, I placed a compass on it and pressed the button, and the needle moved, so it seems to be working. The condition is pretty good for something that's 50 years old. All the included accessories are shown in the photos. 251218