Australia's Best Firm * Due to manufacturing process, thickness given is a general guide and not to exact measurement Miracoil™ Plus has proven to be one of the most innovative sleeping surface developments in the world. Uniquely designed yarn, woven into fabric for a cool-to-touch performance. Protection against odour, stains, and allergies. Spring System : Miracoil™ Plus spring World-renowned spring system with higher coil count and thicker wire diameter for superior back support and long-lasting usage. Comfort Layer : High-Density Foam Cushioning Gives firmer support for increased back support. Miracoil™ Plus Centre Zoning For extra back support where it is needed.