Hexagon socket head cap screws with metric fine pitch thread       

                  Origin practical new public hexangular and cave carry inside 1 kind tight settle bolt, it from inside hexangular(1), Luo pole part(2) and the head(3) constitute, its characteristics lie in, say inside hexangular and cave carry tight settle the head(3) of bolt establish a wreath form flat surface;(3.1)Origin practical new inside hexangular and cave carry tight settle bolt can valid of stalk set and stalk lock tight.