Hmmm... more likely for a Jornada iPAQ, I'd guess. The only HP calculators that take SD cards are the 49G+ and 50, which are mechanically similar and both ~1.5" longer than an N800. (It's kind of a shame the same pouch doesn't fit both, or I'd be grabbing two of these...)

Looks similar to either FA160A#AC3 (different catch arrangement, wider flap), or FA350A#AC3 (short flap, either wrong catch or no SD pockets on front).