LBRNO Anti Bark No Barking Tone Shock Training Collar for Small Medium 5-150 Pound Dog - Stopping Nuisance Barking Humane uses painless tone followed by shock only if barking persists. Automatically increases tone and shock stimulus as barking persists. Microprocessor controlled. Operates on a standard 6 volt battery. Voice Recognition feature minimizes false triggering. Extremely small and light weight,collar length is 18 inch. Effective on dogs from 5 pounds to 150 pounds. APSD-Automatic Power Saving Mode.