We only use high grade clear quartz & Amethyst. The Quartz Crystal Generators will give you the same benefits as the Metal Cylinders/Pads without the restriction of being directly connected to your unit. The Quartz Crystal Generators broadcast 360 degrees and at full intensity transmit frequencies up to 15ft. Placement of the Quartz Crystals. Within reasonable proximity (Same Room). Separate the Quartz Crystal Generators to each side of the room to allow the crystals to communicate with each other. Anyone, (including pet) standing, sitting, or sleeping between the crystals will receive the frequencies being broadcasted. The Pure Quartz Crystals are manufactured through our well stablished company with a history of Rife technology for over 25 years. Even though the Quartz Crystal Generators look the same they have been improved. Leaving the covers on for extra protection will not hinder performance. The Generators are hand-assembled and time-consuming. To avoid lag time please put your order in as soon as possible.