Features:For indoor or outdoor useFor dogs 3.6 kg and upFits neck sizes up to 61 cmPerfect Bark™ detectionWaterproofUses a rechargeable battery (built-in; non-replaceable)Battery usually lasts 40-60 hoursBattery recharges in 4-5 hoursGood/low battery indicatorTwo Colour LED: Shows good or low batter..