The ACV/P1, AC/VP1 is also given in the literature as ACVP1 as Mazda write the Type designation of this vari-μ amplifier pentode in both ways. The AC/VP1 appearing on the earlier version with the screw top cap.
The zinc paint is starting to flake off revealing that the envelope has an internal coating on the glass.
The top screen above the mica. The top cap connects to the anode.
The classic envelope is 39 mm in diameter, and excluding the B7 base pins is 107 mm tall.
References: 1040 & 1043. Type ACV/P1 was first introduced in 1934.