Abstract: New and improved, liquid level adjusting and filtering device is provided, and is operable upon insertion into a container to automatically adjust the level of a liquid as contained in the container to a predetermined, precisely repeatable location, and to filter the thusly level-adjusted liquid. The device is particularly adapted for use in conjunction with test tube-like devices, in the nature of those marketed under the Trademark "Vacutainer" by the Becton-Dickinson Company of East Rutherford, NJ, containing whole blood samples which have been separated as by centrifugation into respective blood cell, buffy and blood serum layers; and is operable in that context to present blood serum samples to automated sample analysis systems at the same predetermined and precisely repeatable location relative to the aspirating probe means of such systems.