We couldn't find one legit EMF expert online or anywhere else that would recommend a radiation blocking case or anti-radiation case. Not the Environmental Health Trust or Magda Havas, or Joel Moskowitz, in fact his site, safeEMR cautions against scams and claims for radiation protection.  So if a so-called "EMF expert" is recommending any kind of anti-radiation case, they probably aren't that much of an expert. 
Perhaps more importantly, what types of radiation are causing, or likely to cause, or are suspected of causing, harm to humans? Is it the “harmonics” from the transmitter? Is it the RF from the circuitry? Is it the primary frequency on which the cell phone operates? This is important to understand. If the problem is the primary frequency on which the cell phone operates then forget the case and ditch the cell phone.
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.
Increases your Body Natural Energy Against Harmful EMF Waves. Vortex BioShield is Safe to Use, It Protects Your Immune System From Penetrating EMF radiation. The Special Combination of Crystals and Minerals Delivers Safe, All-Natural Energy to Defense and Balance Natural Energy Field Also called AURA Best in EMF Radiation Protection - Slim Design Provides Maximum Body Contact.
In the TTAC multiple-segment film, in the seventh segment, I think it is, Ty has a conversation with the scientist who created and got the patent for the Cell Guard and Universal Guard.These are available from http://www.GIAWellness.com, along with single file alignment water and more. To answer your question: the Cell Guard and the Universal Guard are not blockers, meaning that how the device (cell phone, tablet etc.) operates is not being interfered with by having one of them on each device, for example. I enjoy watching Dr. Smirnov explain it to Ty Bollinger!

In 2015, the European Commission Scientific Committee on Emerging and Newly Identified Health Risks concluded that, overall, the epidemiologic studies on cell phone radiofrequency electromagnetic radiation exposure do not show an increased risk of brain tumors or of other cancers of the head and neck region (2). The Committee also stated that epidemiologic studies do not indicate increased risk for other malignant diseases, including childhood cancer (2).
We are often asked why we don't carry the chips, neutralizers, cutesy bugs, and some other cellphone radiation products that are so heavily marketed on the internet. Our answer is simple and honest: our criteria for including a product in our catalog is that it does what we say it does, and its effectiveness can be demonstrated with an appropriate meter.
A cellular phone is basically a radio that sends signals on waves to a base station. The carrier signal generates two types of radiation fields: a near-field plume and a far-field plume. Living organisms, too, generate electromagnetic fields at the cellular, tissue, organ, and organism level; this is called the biofield. Both the near-field and far-field plumes from cell phones and in the environment can wreak havoc with the human biofield, and when the biofield is compromised in any way, says Dr. Carlo, so is metabolism and physiology.

Did you watch any of the videos? A healthy amount of skepticism is appropriate but be careful about just being a Debbie Downer. Admittedly, you haven’t tried all the products and probably aren’t even familiar with them yet quickly offer blanket assessments that it’s all marketing hype perpetuated by an evil Monopoly-man looking guy who just wants to take your money and snicker about what a sucker you are. Good luck with that.
Today’s report, the final one, was about a decade in the making and is the last of several versions that have been released since preliminary results were presented in May 2016. It represents the consensus of NTP scientists and a group of external reviewers, according to the release. In the future, the NTP plans to conduct studies in smaller exposure chambers and to use biomarkers such as DNA damage to gauge cancer risk. These changes in the experimental setup should mean that future studies will take less time.

So you decided you are going to use your cell phone in your car, despite all the warnings. But you have the good sense to keep it away from your head and body! This handy mount can securely hold your phone, iPod, MP3 player or GPS unit with confidence as your drive. Allows easy access and a clear view. Can be used by anyone in the car: driver, passenger, or even in the back seat. Plugs securely into a cup holder and is fully adjustable to any position. Cradle adjusts and can securely accommodate devices up 3.5 inches wide. Completely hands free. Can also be used on boats, recliners or anywhere a cup holder is waiting. You can even do his’n’hers!
Leibovich was very careful to point out in our interview that Cellsafe is not claiming that the radiation absorbed by the body during phone use leads to health issues like brain tumours, male infertility or damage to unborn babies. But the Cellsafe website strongly suggests these links. Its homepage (image below) leads with the phrase "You should be concerned!" in an eye-catching red, and there is as much screen real estate on the site dedicated to information about the dangers of radiation, as there is for descriptions of the Cellsafe products. This information refers to "high levels of RF radiation" in several places, but it doesn't say whether this describes radiation from phone use.
Overall, the reviews of case-control studies seem to suggest there is perhaps no risk of cancer with cellphone use — unless you look at some subgroups (like people in blinded studies or people with long-term exposures). But these reviews are based on case-control studies — which are like the National Enquirer of the science world: cheap and often misleading.
First, you must have a proper meter. To check for magnetic field emissions, an AC Gaussmeter will work. Most AC gaussmeters will have an internal probe. Simply position the gaussmeter on the phone. Note carefully where the meter is positioned. Make a call and watch the readings. Notice the highest and lowest readings, and make a mental note of the "average" reading. Now, insert the magnetic shield, and repeat.
Several studies that will provide more information are under way. Researchers from the Centre for Research in Environmental Epidemiology in Spain are conducting another international case–control study—Mobi-Kids—that will include 2000 young people (aged 10–24 years) with newly diagnosed brain tumors and 4000 healthy young people. The goal of the study is to learn more about risk factors for childhood brain tumors.
Morbidity and mortality among study participants who have brain cancer. Gliomas are particularly difficult to study, for example, because of their high death rate and the short survival of people who develop these tumors. Patients who survive initial treatment are often impaired, which may affect their responses to questions. Furthermore, for people who have died, next-of-kin are often less familiar with the cell phone use patterns of their deceased family member and may not accurately describe their patterns of use to an interviewer.
In fact, nobody can really explain how exactly cellphone radiation could cause cancer, says Christopher Labos, a cardiologist and biostatistician at McGill University. “You don’t necessarily have to understand how something works to prove that it’s dangerous, but it would certainly make the case more compelling,” says Labos, who wrote a detailed analysis for Science-Based Medicine about the recent government cellphone radiation study.
Okay, so Antenna Search isn't really a device but it is a handy service that will tell you how close you are to cellular towers. I punched in my address and found there are SEVENTY-TWO cellular towers and antennas within a 4 mile radius. It lists all the details for each tower – owner, coordinates, installation date, etc. It's a really useful tool for finding out the surrounding risks.
Instead of more animal and even epidemiological studies, he thinks researchers should focus on finding the mechanisms by which cellphone radiation may affect human health. Since we’ll never have an RCT on cellphones and cancer, he added, studies should measure actual cellphone use and exposure to radio-frequency radiation, instead of estimations of how much people are exposed (which most studies currently do).

The frequency of radiofrequency electromagnetic radiation ranges from 30 kilohertz (30 kHz, or 30,000 Hz) to 300 gigahertz (300 GHz, or 300 billion Hz). Electromagnetic fields in the radiofrequency range are used for telecommunications applications, including cell phones, televisions, and radio transmissions. The human body absorbs energy from devices that emit radiofrequency electromagnetic radiation. The dose of the absorbed energy is estimated using a measure called the specific absorption rate (SAR), which is expressed in watts per kilogram of body weight.