Refresh your ThermApparel UnderCool 3, RallyWrap, and UltraCool cooling vests with a new set of long-lasting ExtendedCool cooling packs.

ExtendedCool cooling packs freeze and melt at 70°F (21°C) to deliver strong, comfortable cooling. 

Think of it like a heat exchanger: the packs pull heat out of the blood flowing through vessels near your skin, and your body circulates that cooled blood back through your entire system, bringing your core temperature down from the inside out.

Perfect for heavy gear, full costumes, riggers, outdoor workers, and anyone with severe heat sensitivity who needs serious, long-lasting heat relief.

Key Features

• Replacement cooling packs for ThermApparel UnderCool 3, RallyWrap, and UltraCool vests
• Freezes and melts at 70°F (21°C) for powerful, skin-safe cooling (not painfully ice-cold)
• Provides approximately 2-4 hours of cooling per freeze for long shifts, events, or outdoor activities
• Ideal for heavy gear and costumes: fursuits, armor, rigging harnesses, safety vests, and layered outfits
• Great option for people with significant heat sensitivity who need longer, stronger cooling support
• Works in both humid and dry heat for reliable performance at work, conventions, festivals, and outdoor jobs
• Can be refrozen and reused thousands of times with proper care
• Refreeze: 30 min in ice water, 45 min in freezer, or 60 min in fridge
• Non-toxic, bio-based PCM designed to stay comfortable under clothing without soaking you or your gear

Learn more about how our cooling packs work in our cooling pack guide.