... Durable 2. High elasticity. 3. Stable 4. Excellent supporting bonnel spring Features: 1, Size : all size is available. Base on customer ... Application: used for mattresses 3,Characteristic: The Bonnell spring is the classic Spring Unit, and through the years, proven its worth ... a mat. A round helical crosswise connects each single spring to a spring unit. The quality is guaranteed by the careful ...