A generic modular respirator comprising: a mask assembly having a first end and a second end; a replaceable main unit having a first housing with a first push-fit and twist-release connector to engage the first end of the mask, and a second housing with a second push-fit and twist-release connector to engage the second end of the mask; wherein the mask assembly and the main unit are adapted to perform breathing functions, such as breathing protection, breathing training, breathing measurement and diagnostics; such that the mask assembly is adapted to be quickly fitted to and released from the main unit by actuating the first and second push-fit and twist-release connectors.