154-0705-00
The Tektronix 154-0705-00 is a CRT for miniature scopes, used in the 221.
Standard phosphor is P31. The (non-illuminated internal) graticule has 6 × 10 divisions of 0.203" (5.16 mm) each.
Typical acceleration is -1 kV at the cathode, no post-acceleration.