May Bells Hot/Cold PackThese hot cold packs can help relieve minor aches and pains. To Heat: Microwave for 60 90 seconds in 30sec increments checking for desired temperature. To help with the life of your pack you can place a mug of water next to it when heating up to create humidity and prevent dry out. To Cool: Place pack in a ziplock or plastic bag and place in the freezer for at least an hour. *for added comfort you can place a few drops of your favorite essential oil