... Grade:4.8 ,6.8,8.8,9.8... Double End Bolt,Special Head Bolt,Bolt Maker ,M6 Bolt Dimensions1 ... experiences in screw,bolt,nut,washer,rivet, stud, pin,wrench and so on .2. Our company had good ... strong not break when you tighten the fasteners by wrench ,key ,bit and spanner.When head become thicker ... manufacturers,it is convenient to tighten the fasteners by wrench,,bit,key etc.3.The scrows are also much ...