This is a 20" long and 5" wide rice/flax seed pad. I segment these bags so the rice stays more evenly dispersed. The average heating time is 1-3min but can vary depending on the microwave. You can also warm up your bag in the oven at 325 for about 20min. Check it often during the warming process and shift it around so the rice can be evenly heated. Overheating can result in a burn so please be careful. When placing your bag in the freezer I recommend that they are put in a plastic bag to prevent the freezer smell from attaching to the fabric. Rice bags release moist heat that helps to aide with circulation and pain relief to sore muscles and joints. As your bag cools down, the heat becomes even more penetrating. The heat helps dilate blood vessels and increases the flow of oxygen and nutrients to help heal damaged tissue. It also decrease the transmission of pain signals to the brain and helps relieve discomfort. When used as a cold pack it works by reducing blood flow to a particular area which can significantly reduce inflammation and swelling that cause pain. These bags help with strains, migraines, joint pain, inflammation, PMS, anxiety and depression, fibromyalgia, and post surgery and injection recovery. These are not just for adults, children love them too. They get ease from growing pains, gas pain, sports injuries, a fun way to get comfort when they are sick. They are also great for relieving anxiety and depression. I also can add essential oils to your bag for aromatherapy.the back may be different. I will take special orders and do bulk pricing. Check me out on Facebook and follow and like my page. Serenity Journey Crafts.