Matched Quad 4x Vintage 1960s GEC KT66 Marconi Brown Base Valves Tubes *Tested*

Matched Quad 4x Vintage 1960s GEC KT66 Marconi Brown Base Valves Tubes *Tested* They've been fully tested and are a close match of 4x KT66. There are 2x GEC and 2x Marconi. One has a missing bottom to it, as pictured, but works fine once its place. Very rare to find a quad! Please see the pictures below as these form part of my description.