TechKewl Cooling Dog Coat - MED/LRG-BLUE Ideal for working dogs (police, military, etc) or other caninesthat work or recreate in high heat conditions Outer Material is 100% Cotton - 58F/14C Cool Pax are great for all climates, activates quickly and will last for hours Specially designed for working dogs, these cooling vests use our CoolPax Phase Change Cooling Material (PCM) Sizes: Small/Medium, Medium/Large, Large/XLarge Small/Medium 1 Cool Pax - (10-20 lbs) Back measurement - 14-16 Medium/Large 2 Cool Pax (40-70 lbs) Back measurement - 16-20 Large/XLarge 3 Cool Pax (95-120 lbs) Back measurement - 20-28