Round holes with tight tolerances hold 13 mm tubes tightly for accurate processing, reducing lost samples and potential damage to instruments. Increased efficiency is achieved by using the numbered locations for programming, resulting in higher throughput. Clear concise numbers are silk-screened on the top of the rack for clear visibility. 6 × 5 (90 Place) configuration is the standard for precision instrument racks. Designed for automated liquid handling systems, including robotic sample processing equipment which uses 3 or 4 racks/unit.