You may be looking for Inflatable armbands

An armband is a piece of material worn around the arm over the sleeve of other clothing if present. They may be worn for pure ornamentation to mark the wearer as belonging to group, having a certain rank or role, or being in a particular state or condition. Spring armbands have been used by men to keep overlong sleeves from dropping over the hands and thereby interfering with their use. Armbands may also refer to inflatable armbands used to assist floatation for swimmers.