Mattress coil

Coils are primarily used in the core (support layer) of innerspring mattresses, which is their original use.

A key desideratum is "response range", meaning the change in firmness as the spring is compressed – initially soft, to conform to the body, then hard, to provide support.

In increasing order of response range and cost, the types are:[1][2] While coil springs were invented in the 15th century, they were not used in mattresses until the mid-late 19th century, following the use of upholstery coil springs in furniture and carriages.

Microcoils were introduced in the early 21st century, and as of 2014[update] are a small part of the market.

The bed coil spring was patented by Louis Andrew Vargha.