Sartorius Low Retention Tips feature an extremely even and durable liquid-repellent surface for maximizing your sample recovery and eliminating the loss of your expensive reagents. As a result, detergent-containing liquids with a low surface tension slide off easily from the inside surface of the tip, leaving very little residue behind. SafetySpace Filter Tips with Low Retention Feature Doubled Security for Sample Recovery. The extremely hydrophobic tip surface combined with the safety air gap between the sample and the filter improves the sample recovery in two ways: through better liquid flow, and by reducing the risk of the sample penetrating the filter.