D-vac Tubes, Holders and Needles are used together as a system for the collection, transport and processing of whole blood for the testing of serum and plasma samples. The tubes are made of high quality plastic Polyethylene Terephthalate PET (available also in Borosilicate glass) and the quantity of blood drawn varies with altitude, ambient temperature, barometric pressures, tube age, venous pressure and filling techniques. The cap made of Polyethylene(PE) LDPE and stopper made of Butyl rubber provide a secure tight leak proof stopper.