Regulation of iron absorption and transport. Iron for use in synthesis of heme, iron-sulfur centers and other non-heme iron proteins is obtained from the diet and via release of recycled iron from macrophages of the reticuloendothelial system that ingest old and damaged erythrocytes (red blood cells).
Four-stroke oil is more like the oil used in cars but both 2-stroke and 4-stroke oil serve the same purpose - to keep the engine lubricated. Four-stroke dirt bike oil comes in a variety of weights like 10w-40, 20w-50 and so on. It is not mixed with gas.
Gas. Some cyclists prefer to use gas cylinders to pump up tires. This type of pump is the smallest of all the pumps and will fit into any small pack on the bike. The gas cylinder fits inside a small housing. The housing attaches to the bike's valve and then a small trigger is used to discharge the gas into the tube.