This is the new Electro-Harmonix 300B from Sovtek. They've redesigned the filament of the old Sovtek 300B and put a classy white ceramic base on it. Usually ships within 24 hours.
Price is for a matched pair .
The 300B, in Svetlana's latest and greatest version. The internal structure is well supported and is aligned with respect to the base pins to avoid internal shorts in equipment designed for horizontal tube mounting. The filament is center-tapped to ensure low hum. The Passport gives the exact test results for each individually numbered triode. It is unknown when we will be able to re-stock this tube.