The Sylvania NE-51/B1A is a dual triode vacuum tube that was manufactured in the 1950s. This tube was primarily used in preamps, signal amplifiers and tone circuits. It is a 9-pin miniature tube with a plate current rating of 0.4mA, a maximum voltage of 250V, and a filament voltage and current of 6.3V and 0.3A respectively. The Sylvania NE-51/B1A is still available today and can be used in a wide variety of applications.