This outstanding baby mattress is made of Combustion Modified High Resilliance Foam to comply with BS1877: part 10(1997) and BS7177:1996 for Domestic Use (Low Hazard). The foam core of the mattress provides good support and comfort for your baby. The core is encased in a removable, washable Rochtec fabric which is air permeable and is reversible. Kiddicare Baby Mattress is approximately 4cm thick.