Simplify the following text for a Grade 7 native English-speaking person.
Original: Other units derived from the bar are the megabar ( symbol : Mbar ) , kilobar ( symbol : kbar ) , decibar ( symbol : dbar ) , centibar ( symbol : cbar ) , and millibar ( symbol : mbar or mb ) .
Simplified: The bar ( symbol bar ) , decibar ( symbol dbar ) and the millibar ( symbol mbar , also mb ) are units of pressure .