A blood collection tube is a pre-sterilized glass or plastic tube with a fixed rubber stopper, containing a vacuum which facilitates the draw of a predetermined volume of blood or liquid. Blood collection tubes are predominantly used for blood sample collection in venipuncture, serum separator tubes. Some blood collection tubes tubes will contain additives designed to coagulate, stabilize or preserve the blood sample prior to clinical lab testing. Most blood collection tubes (like BD Vacutainer tubes) are available with a safety rubber stopper and a variety of marking and labeling options. Various brands and sizes are available which will allow your clinical lab to draw different volume sizes of blood.