Does it matter what kind of "medical ID" jewelry i buy? - medical id anklet

I'm allergic, and I want a "buy medical alert" bracelet, but I found some jewelry manufacturers in accordance with other bracelets that (companies such as Universal Medical ID do ").

Is there something special about the "signs of the Medic Alert"? Doctors and hospitals prefer medical alert jewelry other officials?

Is there any reason why you should buy Medic Alert, instead of another brand, like Universal Medical ID?