6B4G Ken Rad JAN CKR Triode - black glass

This 6B4G is a triode power tube made by Sylvania (green label). It has an ST bottle, black plates, and a bottom getter.

These Raytheon 6B4G triode power tubes have ST bottles, black plates, and dual bottom getters. They test on the border of what would be expected for new tubes and are sold as a pair.