... to boil. Remove water from heat. Immerse gel pack in water for 5 minutes.--Cold usage: Lay the gel pack ... pain, sciatica, vertebral pain, improve mucous membrane scar after surgery--cold compress: physical therapy for traumatic hemorrhage, heatstroke, itch, headache, ... ,EVA,TPU2.more than 10 years production experience on heat seal and stitch bags3.Skillful workers and efficient management guarantee ...