i bought one off them bark free , the one u plug in, when dog barks it gives off a sound that we cant hear, just a click sound, 50.00 pounds it cost me, and my older dog kept attacking it, what a load off rubbish,, i cud not take it back cause i had it more that 2 weeks, just to keep trying to c if it wud work,, ps there is indoor ones and outdoor ones, the girl in petsathome, give me wrong one, and had to take it back for indoor, she said they all the same,, silly witch,, the oudoor one is more powerful, it cud have damaged my furbabies ears, long story short i did not work,,
