Yes, I Googled around looking at various options before deciding on this one. The keypad in question has to (a) be re-keayble, i.e. I must be able to put on the keytops that I need, for example, from a cannibalized keyboard, (b) must NOT implement some complex protocol, such as the IBM Keyboard or ADB protocol, USB, etc, and (c) must use "keyboard" switches rather than the typical "toy" keypad switches commonly found on cellphones, game consoles, microwave ovens, etc. (c) is particularly important, since I want the keytops to read 0..F (as in hex) with arrows, shift, and ENTER. Yes, that's only 19, but #20 is a reset, decoded at the other end for those occasions when things go awry. Right now it looks as though I'll be disassembling a keyboard to get this little task done.

I had one with the appropriate hexadecimal legends on the keys and that worked just fine for about 25 years, but I recently parted company with it because a client wanted it for use with a piece of hardware I built for him, though I didn't intend them to use the external keypad. This keypad was attached via a DE9 connector through which it encoded a 20-key array organized as 4x5 switches. Consequently, I snagged a few keypads from eBay, with the idea in mind that I'd rewire the key matrix and simply attach a different cable compatible with my various pieces of lab hardware. Unfortunately, this hasn't worked out as I hoped.

RE