This is the heat pad that is worn like a vest to deliver targeted, soothing heat therapy to the neck and upper back or middle back without inhibiting movement. The cordless heating pad wraps comfortably around the arms and back and its flexible, soft fabric contours to the unique shape of your body to ensure direct contact with the affected areas. Placing the unit in a microwave for two minutes and twenty seconds heats the interior silica beads, causing them to release soothing heat that improves circulation and loosens sore, tight muscles and joints. The unit reverses to provide heat therapy to the neck, shoulders, and upper back or the middle back. The lightweight wrap can be worn over thin clothing or directly on the skin. Chest sizes: Small/Medium 30"-37" or Medium/Large 38"-46".