Gel & Clot Activator Tube is used for clinical biochemistry and immunology. Inside the tube there is a barrier gel present at the bottom, which is a pure substance, very stable in physical and chemical features. After centrifugation, the barrier can effectively seperate the serum from fibrin and cells, while preventing substance exchange between blood cell and serum. As a result, it can keep biochemical caracteristics and chemical components of serum unchanged for a long time.