This adapter allows you to use 6GH8A or 6U8A tubes in place of the difficult-to-find 7199. Tubes are not included.
7199 tubes are no longer in production and NOS 7199s have become scarce and expensive. Fortunately, the more easily-found 6GH8A and 6U8A tube types are functionally equivalent to the 7199, but they use a different pinout. This adapter converts the pinout of 6GH8A and 6U8A tubes to work in places where a 7199 is called for without requiring any other changes.