SportDOG Brand NoBark 18 - Waterproof Bark Control Collar with 18 Levels of Shock - Fits Dogs 8 lb. and up This bark collar corrects barking by using Perfect Bark technology to detect when your dog barks and sending a static correction; the collar must detect the sound of your dog's bark and the vibration of the vocal cords before sending a correction Using progressive correction, the collar starts at the lowest level of correction and automatically raises the level if your dog continues to bark; After 30 seconds of silence, the collar resets to the first level of correction again This no-barking device features 3 selectable ranges of correction (low, medium, and high), with 6 levels per range, to best fit your dog's temperament Replaceable lithium batteries last 3-6 months; features a low battery indicator to let you know when to change the battery; the SBC-18 is waterproof, fitting dogs 8 pounds or larger with neck sizes 5" - 22" The detailed operating guide and a locally based Customer Care Center, available 6 days a week, provide support when you need it By designing our products in the field, with heat, cold, rain, snow, dust, mud, and wind in mind, SportDOG has become the most recognized brand in the electronic tracking and training categories, making the promise to always create "Gear The Way You'd Design It"