The England and Wales Cricket Board have confirmed the return of the 50-over game to county cricket from 2014.
The new CB50 format, which will replace its 40-over predecessor, will see eight teams progressing through to the quarter-finals following eight matches in a group stage.
The first 14 fixtures of the County Championship season will be played on a Sunday and 14 Twenty20 games will be held mainly on Fridays.
The top eight counties will reach the quarter-finals, while the finals day will remain as it is.
More than 25,000 people took part in the ECB survey to determine the changes.