The 6DA4 (along with its controlled-warmup variant 6DA4A) is a 9-pin miniature high-perveance damper diode designed specifically for television receiver horizontal deflection circuits. Engineered to handle high peak inverse voltages and heavy pulse currents associated with flyback sweep systems, its high perveance ensures low voltage drop during conduction. Operates on a 6.3V heater and fits standard 9-pin noval sockets. Available NOS and tested used.