Three (3) pcs. of original British made MULLARD ECC83/12AX7A vacuum tubes.
Grey ribbed plates, seams across the top, copper grid posts, halo getter construction.
Manufactured at the Blackburn Factory in Great Britain.
Codes: B2D3/1022-510, I63 B4J2 and and I63 B1L2/1022-510
Thoroughly tested on calibrated Hickok 533A with excellent results.
Made in Great Britain