Condition: Used/Tested - Premium version of the 6SL7 with gray plates made by RCA, USA. Production code: 6535. Amplitrex test results: Ia=1.9mA, GM=1500 and Ia=1.8mA, Gm=1500. Typical characteristics: Va=250V, Ia=2.3mA, Vg=-2V, Gm=1600.