All animals smell scent in a liquid form.  When a female dog is in heat in the neighborhood every male dog knows it. The reason is that she is releasing the scent in a vapor form because she is so hot. It is like steam coming off of her. As she walks around the neighborhood the prevailing wind is taking her scent all over the neighborhood letting every male dog know she is ready. It is the same with a doe deer and the vapor maker copies that steam or vapor exactly like nature does it. It can not be done any better.The Vapor Maker is the best there is.
If you spray it they will defiantly come.