Innerspring coils are a type of support system commonly found in mattresses. They consist of metal coils that are designed to provide firmness and support while allowing for some flexibility. The coils can vary in gauge, shape, and arrangement, affecting the overall comfort and durability of the mattress. These coils work by compressing under weight and then returning to their original shape, which helps distribute body weight evenly. Innerspring mattresses often feature different coil configurations, such as Bonnell coils, offset coils, or pocketed coils, each offering unique benefits in terms of support and motion isolation.