Cassette systems are most commonly used when larger rooms require more evenly spread conditioned air or when wall space and floor space is at a premium.

Cassettes come in various shapes and sizes with differing numbers of ways in which the air is blown,

Most commonly though 4 way blow cassettes are installed of either the standard size (approx 840mm x 840mm) or Compact cassettes (approx 600mm x 600mm) that fit directly into whole ceiling grid tiles.