those particular types of cylindrical receptacles are especially useful for reducing the amount of electromagnetic frequencies blasting thru the skull by at least 90% (10x reduction isn't nothing); 5G & other modern waves can pass right thru the average human's skull bones; the decentralized health-science community knows this very well - anecdotally, metal enclosures have helped me decrease or totally eliminate the incessant ear-ringing that is worse in cities & better in nature;