Ducts are important components in air conditioning systems, since they are used to transport and distribute the air cooled by the system to the different rooms or spaces in a building. Some types of ducts commonly used in air conditioning systems are described below:

1. Metal ducts: These ducts are generally made of galvanized sheet metal or stainless steel and are durable and resistant to corrosion. They are suitable for commercial and industrial applications.

2. Flexible Ducts: These ducts are made of plastic materials and are commonly used in residential air conditioning systems. They are easy to install and can be adjusted to different shapes and sizes.

3. Fiberglass Ducts: These ducts are made of fiberglass insulation material and are ideal for residential and commercial air conditioning systems. They're lightweight and easy to install, and they're also good at reducing noise.

4. Fabric Ducts: These ducts are made of moisture resistant materials and are commonly used in portable or temporary air conditioning systems. They are flexible and easy to transport.

Selecting the correct type of ductwork for your air conditioning system is important to ensure that the system works efficiently and effectively. In addition, it is important to consider proper duct sizing and overall system design to achieve even distribution of conditioned air.