The four forms of the spray gun function in somehow a different manner to give one the desired results. First and foremost for the pressure guns, fluid is pressurized thus enabling it to flow out. As for siphons, air moves inside to create a siphon that retrieves paint from its reservoir. The gravity feed on the other hand makes use of the force of gravity to allow paint to flow into the air stream. Last but not least, the HVLP guns as they are commonly known function similarly to the siphon and gravity guns. They are specially made to make use of low air pressure to release a large amount of paint. Its low overspray will lead to a high transfer ratio of paint to a given surface and this is an advantage. Other parts of this device are the reservoir which is a cup for holding paint. It mainly holds paint to allow atmospheric pressure through a pinhole vent. The four forms of the gun can hold varying quantities of paint. However the air cap is the part that does the real task. It contains well drilled holes to help produce the best pattern. There are also other parts that facilitate proper functioning of this device and they include the fluid needle and fluid tip.