The Barbell of our new brand GRAYPHITE Line™ has a thickness of 1.6 mm and a ball size of 5.0 mm. The thread of the barbell is externally threaded, its balls can be screwed on the external thread. Please take care that no injuries come into being on the skin tissue, during the insertion. By the way, all the threads in our jewelry collections are standardized, so you can combine the rings, balls, sticks and attachments! All GRAYPHITE Line™ basics are made of titanium, so that they can be sterilized in the autoclave and are absolutely safe for allergy sufferers because of the skin-friendly nature of the material. The oxide layer of the titanium of our GRAYPHITE Line™ piercing jewelry, is optimized in a special process. The result is, that the surface is hardened and has an increased abrasion and tensile strength, as well as maximum passivity and corrosion resistance. Furthermore, this process prevents the "cold welding" of titanium.