Wheels - do I need center thing?

[BigDav782]

https://eauclaire.craigslist.org/wto/d/arkansaw-set-of-4-aluminum-rims/6944230979.html

Looking to pick these up, but notice that the center thing (wheel cover?) is missing.  Will that matter, beyond aesthetics?  Or can I use them as-is?  

Anything else I should be thinking about?

[1986F150Six]

You can use them "as is".

[Gary Lewis]

And if you want to refinish them, here's how I did it: http://www.garysgaragemahal.com/aluminum-wheel-refinishing.html