Our SmartDefender™ units for Cell Towers, SmartMeters, WiFi and Geopathic Zones are designed to help reduce the stress caused by the waves emitted by all devices. The smaller 3" model SD 10 weighs about 6 ounces and can be carried anywhere. The larger 7.5" model SD 50 is perfect for homes and commercial buildings. SD 10 handles an area up to 30 feet in any direction from the unit. SD 50 handles 150 feet in any direction from the unit.