Mullard, British Made Matched Pair CV4003 ECC82 M8136 12AU7 Valves Tubes KB/D Military Spec Grey Box Plates, Halo Getters Matching 631 R2D4 Codes in the Glass Tested Good on AVO VCM 163 1) Ia 11.2/10.9 - Gm 2.2/2.1 2) Ia 11.3/10.9 - Gm 2.3/2.2 100% Book Spec = Ia 10.5 - Gm 2.2 Used, Supplied in White Boxes |