Dear Customer, thank you for contacting Firmoo. The frame is made of metal material which is very lightweight, flexible but durable. However, if metal frames cause a reaction, nickel is usually the culprit because most metal frames are made of a nickel alloy. Moreover, if you are allergic to nickel, I would suggest you choose Titanium frames which are very popular because they are lightweight, durable, strong, and corrosion-resistant. Titanium frame can be made in a selection of different looks, from modern to classic. They are also hypoallergenic, and they retain their shape better than other metals. They bend according to force but retain their shape due to the resistance alloy provides. You can also check here
for more information about our frame materials. Hope this is helpful. Please stay safe and healthy!