Mill Finish is the natural appearance of the aluminum as it comes from the rolling mill (Alcoa, Reynolds, Kaiser, or Alcan) or the extrusion mill. It is as is with no external mechanical or chemical finishing. Extruded metal is considered mill finish. All aluminum has an oxide of some varying thickness. Anodizing is a very heavy controlled oxide.
As they are so small of approximately 5-20 micro-metres in diameter, they do not need valves, as there is a distinct flow from the arterioles supplying the capillary with blood, and the venules draining the capillary within the double circulation.
Blood contains oxygen and nutrients the body needs to survive. The arteries, veins and capillaries are types of blood vessels that transport the vital blood throughout the body. Learn the differences between the types of blood vessels. Capillaries are the smallest blood vessels. 2  They connect to the arteries and the veins. 3  Capillaries are extremely small tubes that average 6 to 8 micron in size; they are too small to see without a microscope.