I sell wiper blades, lots of 'em, Bosch, Anco, Trico, oem. Every one of them is a complete assembly ready to snap onto the arm. Nothing annoys me more than chattering or otherwise noisy wipers and that's why I won't install blades. Blades are the portion of the wiper assembly which actually contacts the glass. They are a royal pain to install correctly, never fit the armature like the originals, and rarely match the quality. It's what dealers all use for warranty replacement.
I know, they put a set on my car (free!) and the first time it rained I couldn't wait to get them off. Free was too high a price for them. I'd suggest to anyone who wants some premium blades which are totally quiet (including in the airstream on a dry day), get a set of Bosch Icons. Installation takes a minute per side. Thank me later.