There are four main types of coils mattresses:
· Open (or Bonnell) coil mattresses have hourglass- shaped coils, which are attached to surrounding coils with a small wire spiral called a helical. This design provides good initial support and works to isolate motion transfer. However, open coils do tend to wear more quickly than other coil constructions.
· Offset coil mattresses have a construction similar to open coil but have a square head, which in theory enables the mattress to contour better. An offset coil is slightly more cylindrical in shape than an open coil which gives it durability.
· Individually wrapped (or Marshall) coil mattresses have an individually wrapped cylindrical coil contained within separate fabric pockets. Each coil is separate so the rest of the bed isn’t disturbed by the movement of the coils surrounding it.
· Continuous coil mattresses have rows of advanced coils made of a single continuous wire. By sharing the weight load across several innersprings, each spring holds its share and integrity longer.