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The Network Billboard (exc Network Home) is a 970x250 non-expanding Rich Media ad unit that sits directly underneath the site navigation. The unit also contains a Ninemsn hosted close ad functionality which gives the user the option to remove the ad after they have seen it and enforce a frequency cap on the ad for the remainder of the day. It also runs with a non-expanding 300x250 leave behind, which should be built per our specs here.