ModelB-75TheModelB-75TesterwasdevelopedtoobtainmoresensitiveresponsetoslightchangesintheupperrangeofhardnesscoveredbytheModelB.Thissensitivityisparticularlyusefulintestingmildsteelandthestrongeraluminumalloys.ForbrasstheB-75coverstherangefromannealedtofull-hard.ThisaddedsensitivityisaccomplishedbyincorporatingapenetratorofslightlydifferentcontourandaheavierloadspringthanusedintheModelB.The20graduationsontheWebsterdialindicatorcoverstherangebetween20and100ontheRockwellBScale.