ECB's Chief Executive Officer Tom Harrison said: "This is a fresh and exciting idea which will appeal to a younger audience and attract new fans to the game.
"Throughout its development, we have shown leadership, provided challenge and followed a process. We will continue to do that as the concept evolves.
"Our game has a history of innovation and we have a duty to look for future growth for the health and sustainability of the whole game.
"There are 18 First-Class Counties, playing red and white ball cricket, at our core and these Counties and competitions will be supported, promoted and benefit from the game's growth."
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