Pocket Sprung Mattress are constructed by inserting coiled springs into a length of cloth, usually calico, which pockets are sewn and coil springs are inserted into.
The material pocket links the springs together without the need for wire links and allows each spring to flex independantly.
The Pocket spring are traditionaly hand side stitched by skilled upholsterers to the outer borders of the mattress.
The use of a perimeter support rod is also used when hand side stitching is not available.