The most recent of these I received was made by Casio - Made in Japan.  The one from before a couple years ago was from Casio - Made in China.  It's stamped on the back of the buckle.  The part number may be the same, but the bands are ever so slightly different.  This newest band I got (made in Japan) is slightly thinner material (about 1.78 mm vs 1.88 mm for the old China band), and the mounting holes are slightly larger diameter.  The marketplace seller I bought from included two new 22 mm long spring bars (pins), but they were much thinner (1.4 mm) than the old ones (1.8 mm) so I reused the old ones.  Even with the old bars, the larger mounting holes make the band at the case a little sloppier fit so now I'm trying to find some thicker ones.  Sure, thinner bars of the right length will work, but they feel "cheap" because the band doesn't feel securely attached.

So yes, this is the correct Casio "factory band" for the AMW-320D watch, but depending on WHICH FACTORY it comes from, the band might not be 100% identical to the one you are replacing.  And whether you get spring bars or not depends on the seller, as Casio doesn't include them with the band.  And even then, the bars you get might not be exactly right either.