The Liquichek maternal serum II control from Bio-Rad Laboratories Inc, Hercules, Calif, is a frozen liquid, human serum-based material designed to monitor the precision of laboratory test procedures used during maternal serum second trimester screening. The control includes AFP, free estriol, hCG, and inhibin A, making it suitable for laboratories performing triple- or quadruple-marker screening. The liquid form eliminates the need for reconstitution, increasing efficiency and allowing samples to be treated the same way as patient specimens. As an independent quality control, the control is not optimized for a specific test system, and provides laboratories greater confidence in patient results. Designed for use on various instruments and reagent systems, the control offers a 3-year shelf life when stored at –20°C to –70°C, and open-vial stability of 30 days when stored between 2°C and 8°C. For more information, visit Bio-Rad Laboratories.