From the smallest to the largest, all of these bracelets are made from the same 5/16" diameter stock.
Twist bracelets fit large so order a bracelet 1/4" smaller than your wrist measurement. For example, if your wrist measures 7" then a bracelet size 6 3/4" will fit comfortably.
Copper is a pure elemental metal, CU on the periodic table. It is reddish brown and is soft enough so that it is malleable which means you can shape and bend it fairly easily. Copper oxidizes and darkens when it comes in contact with the air in the environment. There are many who swear by the health benefits of wearing copper (copper bracelet manufacturers) while others have the opposite viewpoint. Read more about copper . . .