Hampshire wicketkeeper-batsman Calvin Dickinson and pace bowler Chris Sole sign new contracts by the county.
County champions Essex begin the defence of their title in 2018 against Yorkshire at Headingley on 13 April.
Hampshire quartet Jimmy Adams, Fidel Edwards, Brad Taylor and Chris Wood extend their contracts until the end of 2018.
Hampshire chairman Rod Bransgrove wants the county to avoid another brush with County Championship relegation in 2018.
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Watch as a superb over from Harry Gurney sends Notts Outlaws into the final as they beat Hampshire by 23 runs.
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