Groovypets Remote Control Dog Training Shock Collar with Rechargeable Receivers for Humane and Effective Training and Bark Control/anti-bark of Two Small,medium, and Large Dogs:featuring Vibrate and Shock for Each Dog INTELLIGENT PROTECTION CHIP: This bark collar will automatically start a protective sleep mode and then stop working after seven consecutive times of shock. Sleep mode lasts for 1 minute with display screen flickering. Generate a safe voltage of NOT over 7-9V, ensuring the top priority of safety for dogs. 7 ADJUSTABLE LEVELS: Our dog bark collar's Shock mode and No shock mode are optional. Each mode has 7 adjustable levels of intensity and sensitivity. Wide Range of Adjustment is bringing safe and effective bark control to different sizes, no matter small, medium or large dogs SUITABLE FOR ALL SIZES DOGS: Adjustable no bark collar. The diameter of collar belt can be stretched from 1.08 inches to 7.08 inches, which is designed for all 15 to 150 pounds small, medium and large dogs. RAINPROOF & USB RECHARGEABLE: This anti bark collar is Rainproof and Light-weight. Your dog could be running in rain with the collar. Each barking collar contains a piece of built-in 280mAh USB rechargeable battery and 1-2 hour of charging time gives you 14-18 days of working time. LONG SERVICE LIFE AND SATISFACTION WARRANTY: This bark collar for dogs is rechargeable, economical and environmentally friendly. Easy to charge, using high efficiency and lithium battery. If you are not satisfied with our product, feel free to tell our professional customer service team.