This No Bark collar is perfect for small to medium sized dogs, as well as dogs that are sensitive. The YS300 also uses a vibration warning before shock stimulation is activated. Dogtra uses a bark analysis technology to differentiate barking from other outside noises. "Bark Recognition" that distinguishes a dogs barking from its surrounding ambient noises Non-electrical stimulation vibration warning prior to the stimulation 6 intensity levels (2-7) for a wide variety of dispositions Fits dogs as small as 10 lbs (Receiver weight : 4.0 ounces) 2-hour rapid charge Lithium Polymer batteries LED battery life Indicator Fully waterproof