We have recently added two newly listed outdoor media advertising businesses to the portfolio, Ooh!Media (ASX:OML) and APN Outdoor (ASX:APO). Unlike many traditional forms of media advertising, including television and radio which are suffering from structural decline, the outdoor advertising category continues to demonstrate robust growth well in excess of GDP over the past decade. OML and APO are the market leaders, and both have a diverse portfolio of sites under long-term lease. Our real attraction to the space stems from the opportunity for OML and APO to digitise many of the existing static sites. We believe that digitisation is a 'game changer' with large format outdoor digital conversions typically delivering around 4 times revenue uplift per panel and a payback period of three years or less. Both companies are in the early stages of a multi-year roll-out of digital panels that ought to be self-funding. On our forecasts, this should help to underpin double-digit earnings growth for OML and APO for at least the next five years.