Keep your inner fire ignited with the Women's O'Neill Hyperfreak Fire 4/3+ Chest Zip Wetsuit. It prioritizes extreme warmth with the Technobutter 4 (TB4) Firewall while still having all the great features of the classic Hyperfreak. To optimize strength and heat, the TB4 is the next level up from the Technobutter 3. Recycled yarn in the internal liner is infused with graphene, creating a recirculating, fire-hot feedback loop with body heat. This new technology, combined with the exterior fluid seam weld, will stay red-hot, even on the coldest days.