Abstract: A patient interface is disclosed, comprising a chassis portion having a pair of laterally projecting connection portions configured to connect to gas delivery tubes, a seal-forming structure and a vent. The seal forming structure may comprise a central portion configured to seal in use against an inferior periphery of the patients nose and a pair of lateral posterior regions. Each lateral posterior region may comprise a decoupling portion configured to at least partially decouple the central portion from a respective one of the laterally projecting connection portions. The seal-forming structure may comprise rigidising portions, a central anterior portion having a superior portion stiffer than an inferior portion, mid-lateral anterior portions having superior portions stiffer than inferior portions, and/or a lip superior portion having an anterior portion stiffer than a posterior portion. The chassis portion may be formed from a flexible material and may comprise chassis superior reinforcing portions.