Yeah, for wiper blades, at least NAPA's part # is just too generic. The "191" part is no doubt for 19" and many blade makers have some variations of the same length so they add a -1, -2, or a letter.
More Googling.... NAPA calls their blades "Exact Fit...". Trico calls their blades (at least one of their lines) "Exact Fit....". Hmmm