in order to enlarge a sweet area on a ball hitting surface of a golf clubhead , composite structures of two different specific gravities are utilized in addition to structural devices for fixing composite parts . the center of gravity of a golf clubhead is capable of being further distant from a face by utilizing said composite structures , for example , a balance weight fitted into a head body , a face fitted into a head body , a window - like hole provided in a head body etc . in the case of fitting a face into a head body , the specific gravity of said face is smaller than that of a head body , which is provided with a window - like hole , and / or a back crust therein , whereby golf clubheads with ultra wide sweet area can be obtained .