... 3) Anti-bacteria Fuwa : The mattress is made of a independent spring system with moderate hardness. Fuwa is a ergonomically designed ... soft. The internal bladder is made of 70# high carbon independent spring ,which is with strong rebounding elasticity ,and is durable ... ,density: 30kg/ m³8) Insulator: 1000g/m2 felt, hard.9) Independent spring: wire guage 2.3mm,6 turns, Φ78*160cm10) Inner ...