tube size - killer instinct

[TheBortot]

Hi, i'm trying to pick up a Killer instinct cabinet, but it's without the tube. Someone can tell me if 20 inches is a suitable one? Or it's bigger?
Midway fighting games uses a default size of crt?

 

[rewrite]

Internet says 25" in a whole bunch of places.

 

[Mitsurugi-w]

KI shipped with 25" Hantarex Polo monitors.