A survival bubble is a larger version of the rescue ball. A large, 2m diameter, plastic sphere with alternating clear and opaque panels, and a small oxygen tank (capable of supporting one person for two hours) for inflation. Access to the interior is through a conforming plastic seal which functions similar to an air lock. The bubble can be used for life support in vacuum (it can be moved by walking on the inside in treadmill fashion), and can also be used for protection against weather or as a lifeboat on a sea surface. It has good abrasion resistance, but no appreciable armor value. Normal procedure is to sit in one and wait. Most survival bubbles have one panel modified so that a hand can be used to grip or crudely manipulate outside objects from inside the bubble.