Amazon.com: 1pc 6X4 (top) to 6Z4 Vaccum tube adapter socket converter 6X4 TO 6Z4 HIFI Diy : Musical Instruments
6X4 Tube Full Wave High Vacuum Rectifier, Various US Brands. Miniature heater-cathode type twin diode designed for full-wave rectifier operation in compact power supplies. MFR: RCA. SKU: 6X4. New old stock. No
6X4 RCA NOS 1960's pair
NOS MINT in Box Mullard 6X4/EZ90 Tube - Etsy.de
Tung Sol 6X4W Vacuum Tube Black Plates Ruggedized 6X4 Tube - Etsy
6X4 ( EZ90 ) RCA Black Plates O Getter Tube Rectifier Made in USA – Vacuum Tubes Treasures