Great for people who struggle with heat sensitivity or heat-stress related illnesses and those who work or play in hot environments This cooling vest has a clean, adjustable design with no logos or visible pack pockets. Wear this vest over clothing or discreetly underneath; The vest provides sleek front pockets for personal use; The cooling vest is constructed of a durable and machine washable 97 percent cotton, 3 percent spandex fabric Polar Products cooling vests are designed with a patent pending cooling pack arrangement that concentrates the cooling along the spine; This allows for optimal cooling efficiency while minimizing the overall vest weight; The use of separate cooling packs allows the amount of cooling and weight to be optimized for each vest size; This arrangement also allows the wearer to use only the number and location of cooling packs desired for personal comfort Adjustable Zipper Cooling Pack Vests Look good and feel cool! With discreet pockets sewn within. Smaller packs (approximately 4.5" x 6" each) and patent pending spinal pocket placement minimizes weight and maximizes cooling effectiveness! The insulated pockets inside the vest are compatible with your choice of cooling packs: Kool Max Frozen Water-Based Cooling Packs require access to a freezer and offer the highest level of cooling energy for up to 3 to 4 hours. It's science! It takes more energy to charge these packs in a freezer and in return, the packs offer greater cooling energy for a longer time. Cool 58 Phase Change Cooling Packs fully charge (freeze) at 58ºF (14.4°C) and provide a comfortable, constant cooling temperature of 58ºF for up to 2 to 3 hours. Ideal choice when freezers are not available; these packs can be activated in 15 to 20 minutes in a container of ice water!