The only heat source is "pet's body temperature"! This warm wearable blanket, perfect for cold winters, uses heat-retaining and insulating fabric to gently wrap your pet. It features easy-to-use button closures for effortless dressing. Size S Length: Approximately 30cm Neck: Approximately 28-33cm Chest: Approximately 42-48cm Size can be adjusted with 2 buttons. Home-cleaned No individual discounts Bundle discounts available Please refrain from purchasing if you are overly concerned about details.