There are 9 Zones in Vastu as per the traditional Vedic Vastu. They are North, NE, East, SE, South, SW, West, NW and Center.
If any of this 9 zones depleted or contaminated with ani-element or Toilets you may add these zone booster and boost up the energy of the depleted zones.
The easy way to install this is that check the energy through scanner or downswing, of all nine directions. Now, install the Zone Amp where ever required and check again. You will find the amazing results.
This helps especially when you have anti color wall or element in any zones.