Open Coil Sprung Beds
An open coil or bonnell spring system has individual coiled springs which are clipped together at the top and bottom to create a one piece spring unit. Finished with a rod edge support running round the top and bottom perimeter. Variations on this include comfort zones built into the unit, creating firmer areas where the body needs extra support. Another variation is the Silentnight Miracoil system, normally zoned into 3 horizontal sections of different tensions. Made from one continuous piece of wire with a rod edge perimeter, offering you better spinal support and no roll off feeling.
Various filling options are available including Gel, Latex, Memory Foam, Natural or man made fibres.
The rule of thumb being, the more you are prepared to spend - the better the product will be, in terms of quality, comfort & longevity.