Download the 2N4215 datasheet PDF.
This datasheet also includes the 2N4212 variant, as both parts are published together in a single manufacturer document.
2N4212 thru 2N4216 (SILICON) CASE 31(2)
(TO-S) PNPN thyristors (silicon controlled rectifiers) designed for operation in mAlf.lA signal or detection circuits.