Tube racks feature microtiter footprint and alignment guides for a wide array of consistent, reliable, and automated protocols. Recessed rack bottoms allow for safe and convenient stacking. Polyethylene caps are available for secure and convenient sealing of each tube. Available in 8- or 12-strip format, these caps require minimum insertion pressure to obtain a leak-free seal. Each cap is tabbed for easy handling and removal and caps can easily be snapped apart for single tube handling.