This is a TANGO choke coil MC-3-350D. It was attached to a handmade vacuum tube amplifier. Sound did come out of the amplifier, so I believe a signal was being sent. However, due to factors such as the presence of noise and the lack of a proper testing environment, as well as scratches, I am selling this as junk. Please note that, to prevent any issues, no claims or returns will be accepted. Please check the condition of the item in the photos. If you have any questions, I will answer them to the best of my ability. Thank you.