Zig Zag Spring Are Made From Two-Dimensional S-Shaped Wires And Are Also Known As “No-Sag Springs,”Sinuous Springs, “S Coils,” “Zigzag (Zig Zag) Wire” Or “Zigzag (Zig Zag) Springs”. They Are Commonly Used In Ottomans, Chairs (Seat And Back) And Sofas (Seat And Back) And Take The Place Of Coil Springs. Zig Zag Springs Install Quickly And Easily And Don’t Require A Time-Consuming Hand-Tie Job. They Are Fastened With Clips And No-Sag Nails, And They Run Every Few Inches Apart From Front-To-Back Or Top-To-Bottom On Seats, Backs, Ottoman, Etc.