roundie crts

[timmy]

hey all just a curious question about the common 2 color round crts of the 60s the 21fbp22 and the 21fjp22 can these be used as replacements, either crt in either set that has the opposite crt. i dont know how true this is that the difference is the glass in front or the meterial between the crt and the glass. maybe someone can shed some light on this.