A winter essential, Lifesystems\' reusable hand warmers will help keep fingers comfortable in cold conditions. Easy to use, just click the metal disc and massage the pads as the gel begins to crystallise. Place in your pocket or wear inside your gloves and enjoy the instant warming comfort, which will last for up to 90 minutes.To return the hand warmers to their original gel form, add them to a pan of boiling water and simmer until the crystals have completely dissolved. Allow the pads to cool fully before handling.