Using these vacuum cleaner bags is easy. First, turn off your Hoover Regal 9001PH vacuum cleaner and unplug it from the power source. Open the bag compartment of the vacuum cleaner. Take out an old bag if there is one. Then, insert a new bag carefully into the compartment, making sure it is properly seated. Close the compartment. When the bag is full, you'll notice a decrease in the suction power of your vacuum cleaner. That's the sign to replace it. For maintenance, always store the extra bags in a dry place away from direct sunlight. Don't try to reuse the disposable bags as it may affect the performance of your vacuum cleaner and could cause it to overheat. Also, keep the bag compartment clean to ensure a good seal and efficient operation of the vacuum cleaner.