Zigzag springs are also known as "No-sag spring", "Sinuous spring", "Arcless spring", "Serpentine spring", "S-shaped spring", "Snake spring", "S spring", and are mainly made of high carbon steel wire.

They are widely used in sofa (seat and back), chairs (seat and back), and automobile car applications. Zigzag springs can be made flat, curve, round or other shapes according to customers' requirements.

A Serpentine Spring (commonly known as a Zigzag Spring, No-Sag Spring, or Sinuous Spring) is a continuous, wave-shaped piece of high-tempered steel wire that forms the core support system in the seats and backs of a vast majority of modern sofas and chairs.

It is the industry standard for mid-range to high-quality furniture due to its excellent balance of cost, support, and durability.