Some people are allergies about some material, so when they select the frame, they should be careful. In my opinion, Titanium frame maybe a good choice. It is the hottest metal frame material. Titanium frames are very light and durable. They are also hypoallergenic and non corrosive so they won't react with your skin. And titanium frames are available in a wide variety of colors. Of course, titanium or titanium alloys frames are more expensive than most other metal frames. Though titanium ore is abundant in the earth's crust, the high melting point of titanium(approx. 3,000 degrees F) makes it much more difficult to purify and process than other metals.