The Double Core Pillow includes four interchangeable core inserts that provide distinct support options and helps restore the natural curve of the neck while sleeping. This contoured foam pillow provides extra support for the neck, making it an excellent choice for back sleepers interesting in alleviating headaches and neck pain.The Double Core Pillow is constructed from precision cut, high quality foam that provides even support to the head and neck, and allows the shoulder muscles to relax. The core options include: gentle, medium, firm, and extra-firm.As your body becomes accustomed to sleeping on this pillow, you may cravefirmer neck support. The interlocking, interchangeable design allows you to start with the white core for gentle support, then gradually increase the level of firmness by simply replacing the cores until you reach the level of support you prefer.This pillow includes a washable cotton/polyester cover; pillow conveniently fits into your favorite standard pillowcase. Pillow size: 22 inches x 16 inches (56cm x 41cm) with 4 inch (10cm) lobes.