The Visco Therapy Ortho Duo Sleep 1800 King Size Mattressis a firm feel ortho reflex foam mattress which gives excellent support to keep your neck & spine in correct alignment giving you a more healthy & comfy nights sleep. 18cm thick mattress with anti dustmite features & siliconised fiber. Firm feel on one side & medium on the other allowing you to turn the mattress for the comfort you require. Dry cleanable double jersey zip-off cover. Made to british standards/regulations