Functionality confirmed. Serial number stamp seal is missing. Based on the font of the model stamp seal, it's likely a unit from the late 90s to early 2000s, and the solder appears untouched. The plating is gold. There is clouding on the cover. At room temperature (20 degrees Celsius), it measures 7.87kΩ, and the lead wires are approximately 22cm long. Screws and springs are included. It will be shipped in a Duncan box from another product. No returns or exchanges, please.