bm = 1d doub stud jeneralman itilize pou koneksyon ant de pati asye konekte; bm = 1.25d ak bm = 1.5d doub stud jeneralman itilize pou koneksyon ki genyen ant konektè an fè jete ...
According to the force mode of the connection, it is divided into ordinary and hinged holes. According to the shape of the head: hexagonal head, round head, square head, countersunk head and so on.