Serum Tube The red cap tubes are used for serum biochemical tests. The interior wall is finely coated with Clot Activator which accelerates the blood coagulation process after collection. The advanced coagulant formula results in moderate blood coagulation in a relatively short time, avoiding potential hemolysis problems that caused by too rapid clotting. This generates a clear, transparent serum specimen after centrifugation. ; Specification: Æ Cap Color: Red Æ Specimen: Serum Æ Additive: Clot Activator Æ Description: Spray dried Æ Material: Glass or PET Æ Tube Size: 13x75mm, 13x100mm, 16x100mm Æ Normal draw volume: 3ml, 4ml, 5ml, 7ml, 9ml Æ Max. Vacuum deviation: ± 10 % Æ Clotting time: 7^ 30 min. in normal temperature Æ Max. Centrifugation speed: 5000 rpm Æ Storage condition: 4-25 in well-ventilated environment with relative humidity less than 80% .