I've got four like that. Or at least they came like that.
I think the dip tubes may have been brown originally, but they creeped me out.
I pulled them and replaced them with a simple stainless washer and o-ring. Double o-rings work just fine, too.
You can buy the new ones from Williams and other suppliers (I think More Beer has them, or someone else out west) if you want, but standard dip tubes won't work because these are narrower.