Price is for 1 what seems to be NOS tube. With rare triple mica layer and black plates. Produced in the US in the 1960's.
Tested VERY GOOD as follow:
Ia1 = 8.7 mA | S1 = 1.9 mA/V | Ri1 = 9.2 kOhm | μ1 = 17.5
Ia2 = 9.4 mA | S2 = 1.9 mA/V | Ri2 = 9.0 kOhm | μ2 = 17.1
Shipping will be Airmail registered with tracing number. Other shipping methods available on request.