Waterproof, lightweight and durable. Designed for a comfortable and correct fit. 5 intensity levels set instantly with a button. Easy to see light confirms on/off. Bark Odometer "counting feature" reports correction activity. Bark sensor is internal and protected from damage. Choice of contact point length to assure proper contact for short and long coats. Battery-saving "sleep mode". One replaceable lithium battery (included). Battery will last a year in normal use.