4.5 to 5mm. 52 ring bracelets are equivalent to an inner diameter of 5.2cm and an inner circumference of 16.3cm. 36 grams of thick-walled hollow bracelets are semi-solid bracelets and will be 4.5 to 5 mm thick. Ancient bracelets are bracelets made by traditional techniques of ancient methods, such as mold inversion, filigree, hair cutting and so on. Compared with ordinary bracelets, the design adopts a lot of traditional elements, and the appearance presents a matte and matte "ancient" rhyme.