Wide-mouth pathway of flo-top collector permits capillary blood to flow freely into tube, minimizing chance of premature clotting in collection top. The unique �twist-assist� MICROGARD closure significantly reduces blood splatter upon removal, in comparison with other tube closures. 200-400 micro-liter capacity. Made of break-resistant plastic.- Tube, PST Amber, Microgard Closure, Lithium Heparin, 50/pk, 4 pk/cs (Temp Sensitive; Non-Returnable)