Abstract: Two substantially identical inflatable opposed frame elements, each consisting of a single unitary tube performed as by pleats or tucks causing the tube to assume a preestablished configuration when inflated, are connected at four points of intersection of the four tube ends with certain tube segments. Each inflatable element consists of an upwardly extending arch section, an upwardly extending brace section, and a substantially horizontal base section extending between and joining one foot of the arch section and the bottom of the brace section. The other foot of the arch section of each frame element intersects the base section of the other frame element, and the top of the brace section of each frame element intersects the top of the arch section of the other frame element.