Volt Resistance Heated Vest Liner Includes a powerful rechargable lithium battery pack and charger Built-in 4 level microprocessor controller to select desired heat output Provides over 150 degrees of soothing heat on high 2.5 hours and up to 10 hours 3 panel heating system Small 36-38" Chest, Medium 38-40" chest, Large 42-44" Chest, X-Large 46-48", Chest 2XL 50-52", Chest 3XL 54"