Portable air conditioning is usually used as a temporary way of cooling a area. Generally they cool only and use conventional fixed speed compressors with R407c or R410a refrigerant gas. The split type portable air conditioning system has a flexible pipe assembly which connects the inside of the portable air conditioning unit with the outside unit. The outside part is usually the fan and condensing coil (heat exchanger) and is the hot side of the portable air conditioning system. These systems are effective but generally work out more expensive than mono-block portable air conditioning. The mono-block portable air conditioning unit is a stand alone portable system which has the condensing coil (heat exchanger) integral within the assembly of the unit but separate to the evaporator coil. This portable unit has a flexible duct usually 100mm to 125mm in diameter which expels the hot air to the outside of the building. These systems are a very popular portable air conditioning unit.