Construction appears identical to the "blackplate" 12AX7
Trapezoidal getter support
One-piece plate construction, folded and crimped.  Plates are vented by a wide cutout at the top and bottom of the center of the outer plate segments.  Plates halves facing the center of the tube are not vented.  Note single crimp on each flange.
Note that the convex sides of the oval stampings on the flange tabs all face outward toward the glass.  On most RCA tubes, these stampings face alternately in and out. ********************************************************* [Comments from Phil Loarie (hosting editor): It has come to my attention that there is a controversey about this tube's true identity. I have heard comments from experts that this is really a Tung-Sol and I have heard from experts that this is an RCA as some Tung-Sol's were actually rebranded RCA tubes. Since I am not an expert I will leave it to the astute reader to consider both sides of this controversey.]