No shock, just a gentle vibration that does the trick.  Materials: plastic, nylonSpecial features: water-resistant    Size: adjustable, for dogs with weight 11-110 lb and neck size 9-22 inches      Type of battery: rechargeable, holds a charge up to 21 days     Performance: 5 safe stages of sound (beeps), vibration and strong vibration      Box's content: bark collar, reflective strap, user manual, prong covers, USB cable        Dogrook small dog bark collar is a perfect device to stop your dog's barking.    Our no barking collar fits small and large dog breeds because of the adjustable strap.        Using only sound and vibration, Dogrook bark collar is humane and you can use it on small puppies from 6 months.