TechKewl Phase Change Cooling Vest with Nomex� Fire-Resistant fabric. TechKewl Phase Change Fire-Resistant Cooling Vests: Fire resistant V-neck w/zipper closure, and hook & loop girth adjustments Nomex�fire resistant fabric Set of four 6665 Cool Pax Includes Cooler Bag About Nomex�: Nomex\xAC is the brand name for an inherently flame-resistant aramid fiber that is manufactured only by DuPont. Protective apparel made with Nomex\xAC is a collection of inherently flame-resistant apparel manufactured by garment manufacturers that is used to help protect people from thermal hazards. Key Benefits of TechKewl� Phase Change Cooling: Provide cooling comfort and heat stress protection in high temperature environments. Commonly used in extreme heat under work gear, costumes, and other apparel. Phase Change Material releases long-lasting, temperature-specific (58 degrees F, 14 degrees C), cooling relief. Non-toxic, non-flammable, durable, reusable, lighter than water, and does not produce condensation. TechKewl Activation & Use: Simply place in a freezer until solid. Or submerge inserts in ice water for up to 45 minutes. Place inserts to garment pockets. Wear comfortably; repeat steps as needed (or use additional inserts for continuous relief). TechKewl Activation & Use: Simply place in a freezer until solid. Or submerge inserts in ice water for up to 45 minutes. Place inserts to garment pockets. Wear comfortably; repeat steps as needed (or use additional inserts for continuous relief).