Designed to be “leaky”, it permits only a fraction of the RF radiation to penetrate. Exposure to people is reduced (typically 90-99% reduction), and the device usually still works, but with a more limited range. Great for when you permanently or temporarily want to quiet microwave levels without fully turning off the source. Place it over cellphones, cordless phones, two-way radios, smart devices, even wifi routers. Sturdy metal. The two larger units have convenient handle and access holes for wire and cable pass through. Pick the sizes which meet your needs.
Current regulatory standards (SAR Test) only protect us from thermal or heating risks; yet, many hundreds of laboratory studies have found that low-intensity, non-thermal exposure to cell phone radiation can promote carcinogenic mechanisms. Moreover, research on humans has found that 25 years of mobile phone use is associated with a three-fold risk of brain cancer.  –Joel M. Moskowitz, Ph.D. School of Public Health. University of California, Berkeley
The average radiation level of a Bluetooth earpiece is 0.23 watts per kilogram (W/Kg) according to RF Safe. This is 10 to 100 times higher than the amount of radio frequency (RF) exposure needed to create “leaks” in the blood-brain barrier, allowing for toxins (not to mention the radiation itself!) to pass through into the brain. It’s best to just say NO to Bluetooth!
The study specifically used 2G and 3G frequencies — not the frequencies used on more advanced 4G or 5G networks. Researchers exposed the rodents’ entire bodies to the radiowaves for more than nine hours per day, for up to two years. (“A rat that is 2 years old is roughly equivalent to a 70-year-old person,” STAT News reports.) These exposure levels were much higher than what people would experience, John Bucher, senior scientist with the NTP, says in a statement. “So, these findings should not be directly extrapolated to human cell phone usage,” he says.
Hi Ty. I’m an EHS sufferer so now I try to live as free from technology as possible. My landline is connected with a cable, my router is linked to my desktop with a cable. My cell phone just does texts and calls and is switched off 99% of the time. My car is an old Skoda with no Sat Nav, no blue tooth technology and I have an earthing strap running off the rear chassis to remove the EMF’s to earth. At night I dump the power upstairs off along with the lighting circuit, I sleep on an organic mattress with no springs – so no aeril effect attracting EMFs whilst I sleep. Even the alarm clock is a wind up and with black out curtains I get the best sleep ever. Living in a mid terrace house can be a problem but Y-Sheilding both walls has blocked the majority of the neighbours harmful radiation. Guess what, no more EHS symptons.

Four years ago -- before I bought my first iPhone -- I wouldn’t buy certain model cell phones because their radiation emission levels were too high. I became obsessed with researching this in the buying process, especially after finding out that a man I knew died of brain cancer and was an early mobile phone user. Suspicion was that the phone caused the cancer.

As our video points out: Measurements will vary with signal strength and other factors and that includes ambient energy. I talk about ambient energy in a lot of my videos-it's the energy that's in whatever environment I happen to be measuring in that's coming from a source of wireless energy that isn't the subject of what I'm measuring.  My home is not a lab of course, but fortunately it's always measured very low for RF radiation. 
In order to protect the population living around base stations and users of mobile handsets, governments and regulatory bodies adopt safety standards, which translate to limits on exposure levels below a certain value. There are many proposed national and international standards, but that of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) is the most respected one, and has been adopted so far by more than 80 countries. For radio stations, ICNIRP proposes two safety levels: one for occupational exposure, another one for the general population. Currently there are efforts underway to harmonise the different standards in existence.[26]
So, what types of RF are these cases intended to block? If they block the frequency being used by the phone than if the blocking is complete the phone won’t work. If it’s partial than, as noted by the FCC and related in the article, the phone may attempt to compensate for the weakened signal by increasing it’s signal strength, thereby emitting higher levels of radiation itself, and reducing battery life in the process.
Radiofrequency radiation is a form of electromagnetic radiation. Electromagnetic radiation can be categorized into two types: ionizing (e.g., x-rays, radon, and cosmic rays) and non-ionizing (e.g., radiofrequency and extremely low frequency, or power frequency). Electromagnetic radiation is defined according to its wavelength and frequency, which is the number of cycles of a wave that pass a reference point per second. Electromagnetic frequencies are described in units called hertz (Hz).