求好心人说说平头内六角螺栓尺寸是多少?

DIN7991的标准就到M3，其他尺寸即便有也只能算是非标件，这种情况一般会给出几个主要尺寸，然后标注一下，“其它数据参见DIN  7991”  之类的就行了。
圆柱头内六角（DIN912),ISO7380圆头内六角,DIN7991沉头内六角螺丝，标准如下:
M3x5,3x6,3x8,3x10,3x13,3x14,3x15,3x16,3x18,3x20,3x25,3x30,3x35,
M4x6,4x8,4x10,4x12,4x14,4x15,4x16,4x18,4x20,4x22,4x25,4x28,4x30,4x35,4x40,4x45,4x50,
M5x8,5x10,5x12,5x14,5x16,5x20,5x25,5x30,5x35,5x40,5x45,5x50,5x55,5x60,5x65,5x70,5x80
M6x10,6x12,6x14,6x20,6x25,6x30,6x35,6x40,6x45,6x50,6x55,6x60,6x65,6x70,6x75,6x80,6x85,6x90
M8x12,8x16,8x20,8x25,,8x30,8x35,8x40,8x45,8x50,8x55,8x65,8x70,8x75,8x80,8x85,8x90,8x100
M10*15,10*20,10*25,10*30,10*35,10*40,10*45,10*50,10*55,10*60,10*65,10*70,10*80,10*90,10*100
M12*20,12*25,12*30,12*35,12*40,12*45,12*50,12*55,12*60,12*65,12*70,12*75,12*80,12*90,12*100
M14*20，14*25，14*30,14*35,14*40,14*45,14*50,14*55,14*60,14*65,14*70,14*75,14*80,14*90,14*100
M16*20，16*25，16*30,16*35,16*40,16*45,16*50,16*55,16*60,16*65,16*70,16*75,16*80,16*90