摘要 |
In an airtight shelter or container having an impermeable flexible base sheet sealed to an impermeable flexible cover sheet by an inflatable tubular seal within a slotted tubular frame, the slotted tubular frame is formed of lengths of slotted tube secured together by a flexible part annular locking element having a lug or projection resiliently engaging in aligned transverse apertures through mated slotted tubes. |