The JAN 12AT7WC Grey Plate. The 12AT7 tube is commonly used as a phase splitter and also as a reverb driver in many amps. While these are lower in gain than a 12AX7, we discourage using these as a 12AX7 substitute(especially in V1) because of the differences in tube construction and the circuits they are designed for. These are 80's military production, with blue lettering, and a gray anode (plate). While there may be still enough around at the present time, this tube is getting impossible to source now as distribution supplies have dried up. This tube is still a bargain versus current production tubes. Stock up on these great tubes now!