If you think this is just bunk, and you'd like a laugh, read the FAQs on the website [1]... My favourite: >Does the device remove the EMF from the environment? If so can I use a meter to measure EMF? >>The 'electro magnetic meter' can only measure the intensity of radiation which is not changed by our technology nor does it change the quality of connection and speed of data transfer. Well, that's convenient, isn't it…
This is technically true.
>and if you can't sense it it's not there
This is where it gets crazy.
What I find interesting about this is that you never actually have direct access to your senses. For example things in the corners of your vision are fabricated by your mind based on assumptions. See optical illusions. So anyone suggesting that things outside of your senses are not real should first accept that your senses as presented to your conscious mind are not even necessarily 'real'.
In fact your entire reality is fabricated by your mind which is making an internal model of the external world at all times (except when you are sleeping). You only ever see the model never the material world directly.
This is why science is so important. By observing things in controlled environments over and over from many perspectives we can build a more accurate picture of the material world than our senses would normally allow. In addition through the process of replication we can find a model of reality that we can all agree on.
Your senses in the most raw form your body will allow are usually only useful for tasks you evolved to do. Things like reading social cues, catching moving objects and sensing immediate danger.
When people take these senses and intuitions and apply them to complicated things derived from science like electromagnetic radiation (e.g 5G) they break down. But people keep doing it because it feels right, it feels natural. And it is natural just not useful.