Mattress having a spring unit with a single upper peripheral border rod locked within a chamber of a synthetic foam plastic material housing

A mattress comprising a single polygonal border defined between upper and lower terminal peripheral edge portions and upper and lower panels collectively defining a substantially closed chamber, said border and panels being constructed from synthetic plastic material, means for bonding said upper panel to said border upper terminal peripheral edge portion, means for bonding said lower panel to said border lower terminal peripheral edge portion, a spring unit housed substantially in said chamber, said spring unit including a plurality of springs each having opposite upper and lower loop portions positioned substantially adjacent the respective upper and lower panels, an upper peripheral border rod located substantially adjacent said upper panel, means for securing at least selective ones of said springs to said upper peripheral border rod along the periphery of said upper peripheral border rod, said spring unit being devoid of a lower peripheral border rod at said springs lower loop portions, means for peripherally interlocking said upper peripheral border rod substantially against movement relative to said border and upper panel, said upper peripheral border rod being substantially interlocked against lateral and longitudinal movement by an upper inner peripherally extending distorted corner of said chamber defined by said upper panel and said polygonal border in interlocking relationship with said upper peripheral border rod, and said spring unit being devoid of fabric pockets adapted to house springs.