The size. If I remember correctly, there were NO printed indicators on the box, only a post-manufacture sticker on the extreme lower left of the front of the box. Distinctly different from the spec list. Also, the sticker was about 1/8" high and was sort of peeling off before I got the box. The whole thing was a previous return anyway. I'm starting to believe that there aren't any "new" items in our local Staples. I think they just use it as an outlet for returns...

Of course, when I asked the employee at Staples about IIIc compatibility, he flipped over the box, looked at the spec list, and said, "Sure, it'll work."