Inflatable device and method of inflating same

An inflatable device, comprising:

• a mouth having an open position and a sealed position;
• a body having a distal end that is closed, and a proximal end, wherein the body defines an interior volume in gaseous communication with the mouth when the mouth is in the open position, wherein the body has a flexible body wall extending from the distal end to the proximal end, wherein the flexible body wall is air impermeable;
• a structural distal ring that is more rigid than the flexible body wall and which is connected to the flexible body wall and which is positioned between the proximal end and the sealed distal end;
• and
• a structural proximal ring that is more rigid than the flexible body wall and which is connected to the flexible body wall and which is positioned between the proximal end and the sealed distal end, and is proximal relative to the structural distal ring,
• wherein the body is collapsible to a collapsed state in which the body has a collapsed length and in which the structural proximal ring is located a first distance from the structural distal ring;
• wherein the body is inflatable to an expanded state in which the body has an expanded length and in which the structural proximal ring is located a second distance from the structural distal ring, wherein the expanded length is greater than the collapsed length, and the second distance is greater than the first distance;
• and
• wherein the interior volume is sealed when the mouth is in the sealed position.