The Percell Pet Vent allows your pet to safely enjoy fresh air while riding in your car. Fitting a Pet Vent can alsoprovide vital ventilation whilst your car is stationary. For optimum ventilation fitting a second Pet Vent in the opposite door will help to set up a cross-flow of air helping to keep the inside temperature from reaching dangerous levels. The Pet Vent fits best in the rear passenger doors. Remember it is also wise for your pet to be tethered in a car belt especially designed for dogs.