Yep, all parts are OEM/factory issued parts -- not imitations. But yes, the bummer is the min shipping charge is $9.75, especially for a $3 part.
1. Even though the DIN sized mounting sleeve have the same dimensions, the mechanical connections to the manufacturer's (and sometimes even model specific within that same manufacturer) chassis can be different. For instance, Alpine has side sliders that hook onto the sleeve while Eclipse has side spring plates (I'm unsure what Pioneer uses). Unless you fabricate a custom mount, play it safe and use the correct manufacturer's mounting sleeve. Besides, it should come with your new H/U.