The Genalex U77/GZ34 is an audiophile rated ultra efficient indirectly heated dual diode, full-wave vacuum rectifier. Providing a mere 10V drop in B+ (plate voltage) at full current demand, this rectifier insures a strong, dynamic response to your sound. An excellent and reliable choice, the Genalex U77/GZ34 comes with a classic blue base, highly stable tandem supported getter cup, industrial thickness dual mica spacers and full 30mm length internal plate structures. This tube is an excellent replacement of any GZ34 and 5AR4 rectifier tube.