(!!!!!) (Recommended Pair) 12BH7A GE gray oval plates NOS 1965 (11/15.5ma and 13.6/11.6ma)
(!!!!) (Best Single) 12BH7A RCA NOS 1960's (11.6/12.6ma)
(!!!!) (Single 1950's) 12BH7A RCA branded Westinghouse narrow black plates NOS "U" getter mid-1950's (10/7.8ma) (1st series made)
(!!!!) (Single 1960) 12BH7A RCA "D" getter like new 1960 (9.4/8.8ma) (same Gm)
(!!) 12BH7A RCA gray plates used/good 1960's (8.0/11.2ma)
(!!) 12BH7A RCA gray plates used/good 1970 era (8/9ma)
