This reusable heating and cooling pack is made of dry cherry seeds with a cotton linen outer shell. The pack can be warmed in the microwave or cooled in the freezer for hot and cold therapies. Contains no chemicals, and the all-natural cherry seeds will hold temperature very well. Does not require electricity. Ways we enjoy our cherry seed packs around the house include: relaxing neck tension, relieving shoulder pain, releasing lower back tension, swollen knees, soothing carpal tunnel pain, increasing circulation to the uterus for fertility and cramps, warming breasts before nursing or pumping, cooling breast tissue after pumping, warming the sheets at bedtime, easing plantar fasciitis. Doulas and moms love our product for delivery, postpartum, and baby care! The process of conceiving, carrying, and having our twins was the inspiration for production of these cherry seed packs. We wanted to share the benefits of this natural, chemical free tool with the world.