BD Vacutainer Serum Separator Tubes (BD SST II Advance) are used to obtain and separate a serum sample. The tubes are available in a range of sizes in plastic and can generally be identified by a gold cap. BD SSTTM II Advance tubes contain Silica to activate clotting of the specimen and a gel that forms a barrier between the clot and the serum after centrifugation. BD SSTTM II Advance tubes contain an acrylic based gel and unique gel design with optimised slope. This design enables centrifugation flexibility which provides increased laboratory workflow and process efficiency. The minimum recommended clotting time for BD SST II Advance tubes for patients without anticoagulant is 30 minutes.