Rubber latex refers to a stretchy substance that comes from the sap of rubber trees. It is used to make things like gloves, balloons, and elastic bands. Full definition
The result is a next generation, natural rubber latex - based foam that sleeps cooler than a traditional mattress and supports your body so you can get a good night sleep. (myessentia.com)
Does preference of rubber latex over silicone meant sucking problems? (babycenter.com)
Natural rubber is another option, as long as your child does not have an allergy to natural rubber latex. (mindbodygreen.com)