An Open Coil spring unit is made from a continuous piece of wire. This wire can be made from various different gauges of wire, ending in differing firmnesses.

The idea behind an Open Coil spring unit, or Continuous Springs as they are sometimes known, is that the spring unit can be made quickly, efficiently and therefore for little cost. Open Coil spring units tend to be the reserve of the entry level models on the market. However, some manufacturers have perfected the technique and the end result is extremely successful.

A single piece of wire will be placed in a machine, bent into coils. Each coil will be joined at the top, the bottom or both and the result is a spring unit made of one wire. The reason this works well, is that the springs can support one another and share any weight or pressure across the surface.

Other methods of spring units include Twin Sprung or Pocket Sprung.