Supercoil Spring System. Fibre Fillings. Medium – Firm Tension.The Ortho Comfort by Airsprung is from the comfortably firm range, it offers medium to firm support. The mattress contains a supercoil spring system which is an extra heavy 12.5 gauge bonnell spring system which is made from a high tensile wire built for an increased performance. The Comfort Ortho by Airsprung is filled with man made fibre fillings and is suitable for a wide range of divan bases, or bedsteads that are available on our website.