Mullard GZ 30 Fat coke bottle Rectifiers Two Mullard Full wave rectifier GZ30 ~Fat Coke Bottle ~Black Plates. GZ30 version "O" getter halo. Yellow logo. Never used but tested on Avo 160. RMS input per anode is max. 350 V. with a rectified current of max 125 ma. Bottom D-shaped solid getter and black anodes. Very well built and excellent sounding NOS rectifiers. I use them in my head and pre. Refined detailled smooth sounding as best described Excellent for Head amp, Pre and Phono or Se. New never used tested