Old frequency counter circuit board that uses Nixi tubes. See the photo of them working before the frequncy counter was dismantled. Sold as is, non working, parts only but you can see them working. For size compairson, the frequency counter was 3.5 inches high (2 Rack Units) as shown in the pictures. The frequency counter chassis shown to see that the nixi tubes are working. It is not included in the sale. The circuit board is loaded wtih 7400 series TTL chips that are in sockets. Thanks for your winning bid!