An Open Coil spring unit is made from a continuous length of wire. This wire can be made from various different gauges thus giving differing firmness. The idea behind an Open Coil spring unit is that the spring unit can be made quickly, efficiently and therefore for less cost. Open Coil spring units tend to be the reserve of the entry level models on the market or for children’s mattresses.

Each spring coil is joined at the top and bottom creating a single spring unit so that the springs can support one another and share any weight across the surface. Other methods of spring units include Mira Coil and Pocket Spring.