The most crucial aspect of any barrier-free pet containment system is training.
For the first few weeks after the system is installed you need to follow a routine training program to accustomize your pet (dog or cat) to the boundaries of the system.
For most animals the association of white flags with an audible beep and a few corrections teaches them their limits very quickly. Some animals are more boisterous or impulsive than others and cats naturally exhibit a distinctly feline attitude to being given limitations. They are probably harder to train than dogs but will learn with patience and consistency.

Training flags are used to teach your pet the limits of the avoidance zone (the signal field) which is, effectively, invisible. You will teach him the response by pulling him back into the safety zone if he hears a beep.

He will learn by experience that to enter the avoidance zone (and ignore the beep) results in a correction. All dogs and cats respond differently to this mild stimulation and the strength of the signal will have to be adjusted by trial and error. In all cases it is adjusted gradually.

With xxxx settings for fence width and strength on the transmitter and a further xxxx settings for correction strength on the receiver/collar, almost any dog or cat can be trained in about two weeks (although further reinforcement is recommended for a month at least).
Adjustments are easily made on an individual basis and flashing lights on the collar show if your pet is challenging the fence or not. Although the correction is not particularly pleasant, most pets, once trained, never test the fence beyond the audible warning to the point of correction again.