BD Vacutainer® SST II Advance Tubes are made of polyethylene terephthalate (PET) and spray-coated with silica. Prevents the contamination of the serum from the separated cellular components. Features an inert, stable gel that separates the serum and the blood clot during centrifugation. The type of gel used enables short centrifugation times. Using SST™ II Advance, routine analytes in clinical chemistry, such as potassium and glucose, are still stable after a week of storage at 2–8°C. Clinical evaluation of special chemistries (such as therapeutic drugs, proteins, peptides, steroids and vitamins) demonstrates a high degree of stability with the acrylic gel in these tubes, which is a distinct advantage during transport and storage. Advantages of gel tubes ensures a stable barrier between serum and clotted blood, therefore better analyte stability and sample quality. It optimises work flow: short centrifugation time, sample processing and archiving in the primary tube. It also ensures no possibility of misidentification due to the use of secondary tubes.