"Dual firmness" refers to a product or item that is made with two different levels of rigidity or hardness. It means that one side is firm while the other side is softer or more cushioned. Full definition
This vehicle possesses a comfortable interior that comes with dual firmness foam seats, which provide added comfort and support. (wilsongm.com)
Much like the Moonlight Slumber Little Dreamer, it also has dual firmness with high density thanks to the thermo - bonded core that assures a firm support to your child while sleeping. (followmum.com)
The Glass Baby Bottle is giving away a Naturepedic No - Compromise Organic Cotton Classic Dual Firmness Crib Mattress valued at $ 299.00! (theglassbabybottle.com)