STaK-Chex is a whole blood assayed hematology control which offers complete assay values for the five-part white cell differential. White blood cell percentages vary for each cell type and are within clinically significant ranges. The precision and accuracy of the instrument’s laser is controlled each time STaK-Chex is analyzed. The control features cap-pierceable vials for autosampling. Its long shelf life reduces the number of shipments, associated costs and time spent performing lot-to-lot correlation. Each vial label is barcoded to assist with quality control data collection, eliminating the possibility of transcription errors. STaK-Chex is compatible with the Beckman Coulter LH500 and HmX hematology analyzers.