6HG8/ECF86 RCA Medium-Mu Triode Sharp-Cutoff Pentode Miniature Vacuum Tube 9-Pin NOS New Old Stock in Box
List of vacuum tubes - Wikipedia
6T4 SYLVANIA Audio Vacuum Tube Valve - Bangybang
Vacuum tube - Wikipedia
MIXED LOT OF 4) 6BZ7 Vacuum Tube HIGH-MU TWIN TRIODE
Tube NOS #353 Westinghouse 7GS7 Med-Mu — Parts Connexion
6463 GE Medium Mu Twin Triode Tube. Designed for use in industrial equipment as characteristics of stability and long life are required. New old stock. No longer available for export. MFR: GE.