Reusable inserts for the AlphaCool Tundra Phase Change cooling vest. These water-based non-hazardous inserts hold a 64F temperature for 3-4 hours and can be recharged by being placed in the freezer for approximately 3 hours. Features: AlphaCool Tundra Phase Change cooling vest Cooling lasts 3-4 hours Reusable over and over! These water-based non-hazardous inserts hold a 64F temperature for 3-4 hours Can be recharged by being placed in the freezer for approximately 3 hours.