Use these packs to relax muscles, relieve pain and soreness in arthritic joints, relieve stress and much more. The king pad is great for large areas such as the back and spine. The medium is for the arm, shoulder and elbow areas. And the mini is ideal for cervical, throat and jaw area (as in TMJ), as well as the ankle and wrist area. Includes removable flannel cover. 3 year limited warranty.