... voice signals from an infinite distance.Now also available with bluetooth collar, to quietly communicate from unlimited distance! Micro EarPiece Secret ... , across electromagnetic fields Receiving distance: 50 70 cm (not for Bluetooth solution) Standard Zinc-air battery: type 5 1,4 volt ... secret ear: about 70-100 cm.Ear-GSM kit with bluetooth collar includes: Micro Earpiece Secret Ear ...