An elastically distensible folding member is disclosed. The folding member can be formed with a wall that is substantially shaped as a tube when the folding member is in a relaxed (i.e. unstressed) state. The tubular shaped folding member defines a tube axis and can have an axially aligned slit that...http://www.google.co.uk/patents/US7413558?utm_source=gb-gplus-sharePatent US7413558 - Elastically distensible folding member
