Two, NOS RCA JAN CHY 5692 tubes, military issue, the long life/high reliability 6SN7GT. Red micanol bases, flat black plates, reinforcing rods. The 5692 is of course the ruggedized, low microphonics, low noise, high reliability, long-life version of the 6SN7GT tube and can be used in applications calling for the 6SN7GT.