Bark Terminator 2 Anti Dog Barking Shock Collar Humane, uses painless tone followed by shock only if barking persists. Automatically increases tone and shock stimuli as barking persists. Microprocessor controlled, Water resistant, rain and snow will not affect operation. Voice Recognition feature minimizes false triggering, Extremely small and lightweight. Effective on dogs from 5 pounds to 150 pounds, nylon strap adjusts from 5" to 24", 6 volt battery