I am very touched by your piece of filial piety. For this reason, I pertinently tell you: do not go to buy titanium germanium bracelet. That's the stuff of business hype. As a metal, if it does not have a radiating effect, you spend money for nothing, which is the best harvest; if it really has a radiating effect, you really harm your parents. This is because the beneficial natural radioactive sources of metals that can be utilized by mankind are still almost non-existent, and radioactive sources like radium and germanium, which have the ability to kill humans, are the ones that we must stay away from. So, it is recommended that you must discard this idea immediately. If it was really beneficial to human beings, the medical organizations would have passed the accreditation and promoted it to the world long ago.
Based on what you said about your parents, my mentor suggests that you get them a better massager. For example, a whale-style handheld massager. They can massage their neck every day in order to improve the blood flow in their neck. They can also use it to massage their legs, waist, and abdomen when they are tired. Very beneficial. The price is probably right around $100. If you still want to spend more, add a pedicure foot wash basin, which is also considered to be a substitute for you, so that it can do a filial duty in your parents' side. The foot wash basin should go to a regular big shopping center to buy one made by a regular manufacturer. The price is 300-500 dollars. What I am suggesting to you are physical therapy equipment to improve blood circulation.