Picked up an nos crt, but what is it?

[bandersen]

P12 is the orange radar phosphor. P7 is a dual phosphor. Short persistence blue and long persistence yellow as used for radar displays. I hooked up a different model P7 CRT to a vintage TV once. It's a freaky display to watch for sure, but could be used for testing.
You could probably sub it in for a 10BP4, but the base is different so you'd need an adapter. Here's some data for it: http://www.scottbecker.net/tube/sheets/141/5/5FP7B.pdf