No better fit, no better function. Our patent-pending Ultimo CoolVest is designed to fit like a second skin, assuring the most effective transfer of temperature possible in a cooling garment. The garment itself is virtually weightless - and our innovative design distributes the weight from the coolants throughout your body. 100% Cool matched with 100% Comfort. Every textile in the Ultimo performs a job: Exterior spacer knit insulates CoolPaks against the environment, yet is breathable. The Interior textile provides moisture management and antimicrobial properties. The Ultimo is what happens when the best of form meets the best in function. Sizing: Our garments are sized by height and weight. If your height is above or below average and you are uncertain what size to order, do not hesitate to contact us by email or phone. There is flexibility with each size. Size 0: For slight physiques of approximately 100 - 130 lbs. Size 1: For the athletic physique of approximately 130 - 165 lbs Size 2: For weights of approximately 165 - 195 lbs Size 3: For weights of approximately 195 - 250 lbs Note: Please remember to factor height into your evaluation of size. For example, a person 5'4" at 175 lbs would wear a Size 2 Ultimo. A person 6' 0" at 175 lbs would wear a Size 1. Features: Ultimo CoolVest is designed to fit like a second skin The garment itself is virtually weightless Our innovative design distributes the weight from the coolants throughout your body Exterior spacer knit insulates CoolPaks against the environment The Interior textile provides moisture management and antimicrobial properties