L4 is the head tennis parameter, which is an abbreviation and only represents this series. There are also intelligent Agassi, Liu Jin L4, microgel L4 and so on. At present, the latest model is Youtek(D30 space material) L4, whose full name is Head YOUTEK Radical. There are three models: Pro: (98 face, Murray model), Oversize( 107 face, Agassi model), Lite (lightweight version). These three L4s have been on the market since 2009. I haven't seen the updated models yet, so they will be in front of Wimbledon at the earliest.