This versatile pack from Steroplast can be used either hot or cold to relieve a variety of aches, pains, sprains, and other injuries. The non-toxic gel filling remains soft when frozen, enabling the pack to contour to the body and can also be heated up using a microwave or pan of boiling water. Size: 13 x 25 Centimetres Hot Application - Microwave: Place gel pack into microwave for approximately 30 seconds on high temperature. After this time, check that the correct temperature has been reached. If not, further exposure should be in 15 second intervals. CAUTION: DO NOT OVERHEAT. Times are based on a 600W microwave. Adjust heating times to suit the power of your microwave. Hot Application - Hot Water: Bring water to the boil, remove from heat and immerse the gel pack for approximately 4 - 10 minutes. After 4 minutes, check every 1 minute to see if the correct temperature has been reached. Cold Application: Store in the freezer so that the pack is ready to use in case of injury. Approximately 1 hour is required to freeze gel. Bullets change to: Re-usable Hot/Cold Pack To Heat, microwave for 30 seconds only To Cool use very cold water or Freeze Tough Material Construction, can be re-used hundreds of times