Para 4 is an assayed, whole blood hematology control for evaluating the accuracy and precision of automated, semi-automated and manual procedures that measure blood cell parameters. The control mimics the appearance of patient samples and is available in three clinically significant levels. Its long shelf life reduces the number of shipments, associated costs and time spent performing lot-to-lot correlation. Para 4 is available packaged in glass vials or in squeeze dropper vials for accurate sample dispensing, eliminating the need to pipette.