A virtual interface is disclosed. In one aspect, the method includes: displaying a media program on a media display device; indicating, while the media program is being displayed, an item associated with the media program is available for purchase; receiving authentication information of a prospective purchaser of the item; and completing a purchase of the item in response to the authentication information. Such filter units can be placed in the stream of a mobile fluid and can remove a particulate andor fluid mist load from the mobile stream. Inter-cluster links are formed between interconnection controllers of different clusters. An embodiment FinFET includes a fin supported by a semiconductor substrate, the fin extending between a source and a drain and having a channel region, and a gate stack formed over the channel region of the fin, the gate stack including an N work function metal layer comprising an oxidation layer on opposing sides of a tantalum aluminide carbide layer.