IBM Model M Clicky Keyboard 1395674 Vintage Buckling Spring 1990 TESTED No Cable$49.99 OBO + shipping
This terminal-emulator Model M variant is so seldom seen, it's mentioned only twice here on GH and not at all on Deskthority. So you'd think this professional seller would've provided clearer shots of its cool legends and sub-legends, as seen here on one of the few previously known examples (which, unlike the one being sold, is missing a couple of caps):
Unlike M's made for actual mainframe terminals (and thus, incompatible with PCs without specialized converters), this one was made for standard PCs running terminal
emulation software. So it can be connected directly to a PC's PS/2 port, using a
standard Model M SDL->PS/2 cable; or to USB, using the aforementioned cable and an inexpensive
PS/2-to-USB converter.
And yes, the Pause and Esc keys have original blank caps. ("There is no Escape"—that sounds ominous.)