This tubes have silica particles added to trigger the coagulation within an acceptable time Material: PET & PP Type of Additive: Clot Activator Size: 13X75 mm, 13X100mm Capacity: 1 mL, 2mL, 3mL, 4mL and 6mL Available in: Vacuum and Non Vacuum Colour Code: Red Available Packaging: Inner Packaging 100 pieces, Outer Carton Packaging 1200 pieces Used for: Chemistry enzymes, electrolyte Immunology presence of antibodies to a pathogen Serology protein made by human immune system Blood bank cross matching of blood types.