Safety jacket is to keep the wearer alive and afloat should they unexpectedly end up in the water or elect to participate in watersports such as skiing or wake surfing.
According to the Malaysian Maritime Enforcement Agency, personal flotation devices come in various types and ideally should be chosen to best match your activity or boating conditions.
TYPE I: All waters, especially open, rough, or remote waters where rescue can be delayed.
TYPE II: Calm, inland waters where there is a good chance of rescue. Not good for long terms.
TYPE III: Calm, inland waters where there is a good chance of rescue, amazing comfort, and ideal suit.
TYPE IV: All waters where help is present. Not suitable for the long term in water.
TYPE V: Design for specific activities; check approval condition on the label.
Sources: Malaysian Maritime Enforcement Agency,