The lightweight Kool Max Zipper Front Vest (KMVZ) efficiently and effectively cools the body in any environment, under or over clothes. Reusable, non-toxic, water-based cooling packs provide constant cooling for up to 4 hours. The Small vest includes eight (8) packs, M/L and L/XL vests include eleven (11) packs, and the XXL vest has twelve (12) packs. The 4.5" x 6" packs fit into insulated pockets inside the vest. The pockets have a comfortable all-cotton fabric to protect the skin and an insulated outer composite fabric to direct the cooling energy toward the body. The location of desired cooling is easily controlled by which pack pockets are used. Place the packs in the freezer until they are frozen hard; for best results, store in the freezer, so they're ready when you are! Simple and unisex design with a zipper-pull front. Adjustable at the chest, waist, and shoulders. Lightweight vest weighs 3.7 lbs. to 5.5 lbs. Weight may be adjusted by varying the number of cooling packs used. This is an excellent vest for wearing under uniforms or protective clothing. Available in Blue or Khaki.