Description Overview 33 refers to the density (kg/m³) of the foam. The 35 density has certification to pass the CTB 117 for California. A range of about 70 foam densities is available. Specifications 170 x 200 x 17.5 cm (10 cm bio + 7.5 cm visco). 170 x 200 x 13.5 cm bio 40 density. 170 x 200 x 16 cm bio 40 density. 170 x 200 x 13 cm 33 density. 170 x 200 x 17 cm 33 density. 170 x 200 x 16 cm 35 density California test. Shipping Approximately 65 non-compressed or 100 compressed mattresses per 20 foot container.