IBM branded, GE manufactured 5965 tubes. These have an amplification factor very close to both 12AY7 and 12AT7, and share the same pin out and other similar characteristics.

In most vintage amplifier circuits, you can drop one of these in in place of the other with a sightly smoother sound. The lower plate resistance can also add some chime in subsequent stages. However, microphonics can make them unsuitable for V1 use, so these are best suited for phase inverter and reverb driver slots.

All tubes will be tested for life and transconductance on a Hickock 533a mutual transconductance tester. Matching is available on request. The print quality varies, per the photos, but all have the 5965 text visible, as it is etched into the glass.