A pneumatic mattress (1) has two edge cells (2,3) and a even plurality of transverse inner cells, arranged in adjacent pairs as alternate cells (4) and cells (5). An umbilical inflation hose (6) is provided with three internal pipes (7,8,9). Pipe (7) receives constant pneumatic pressure and has a pipe extension (17) to pneumatic connectors (27) for the edge cells (2,3). Pipe (8) receives alternating pressure for cells (4) via extensions (18) to connectors (28). Pipe (9) receives alternating pressure for cells (5) via extensions (19) to connectors (29). The connectors (28,29) are T connectors having a stem welded into the bottom of their cells (4,5). The connectors (28,29) are in lines (38,39). Each cell has a connector at both ends, whereby there are lines (38 & 39) at both sides of the plurality of inner cells (4,5). The edge cells (2,3) are formed by folding and seaming a sheet of polyurethane material leaving a pair of strips (11) on top of each other. These have two lines of dumbbell apertures (48, 49) on the lines (38,39), rounded at both ends both for avoiding stress concentration. Each connector (28,29) is passed through its aperture (48,49) on the appropriate side of the mattress. Thus the edge cells are physically connected to the inner cells. The pipe extensions (18,19) are added between the respective connectors, establishing the pneumatic connections to the cells. The entire mattress is pneumatically and physically interconnected using only the connectors and the apertures in the flaps.