One of the most common is British bolt, American bolts Specification of British bolts: Common specifications are 2 #; 4 #; 6 #; 8 #; 10 #; 12 #; 1 / 4; 7 / 32; 5 / 16; 3 / 8; 1 / 2; 9 / 16; 3 / 4.Unit in (in.). British nominal length specifications: common values are 1 / 4,5 / 16,3 / 8,7 / 16,1 / 2 5 / 8,3 / 4,1,23.Unit: in (in.). The American standard is made of British system, and the national standard is made of public (meter) system. American standard general thread description: 0 # -80,2 # -56,4 # -40,6 # -32,8 # -32,10 # -24,1 / 4-20,5 / 16-18, etc., this description in front refers to the thread address diameter, behind is refers to how many teeth in 1 inch. The metric thread description: M3-0.5, M4-0.7, M5-0.8, M6-1.0, M8-1.25, etc., this description before also refers to the thread address diameter, then refers to the tooth distance. Except for the thread, other sizes are also different: if it is a hexagonal nut, the thickness is not the same size as the opposite side: if it is a screw, the head size is also different.If any product meed your demand, please feel free to contact us. We're sure your any inquiry or requirement will get prompt attention, high-quality products, preferential prices and cheap freight. Sincerely welcome friends all over the world to call or come to visit, to discuss cooperation for a better future! We can meet the various needs of customers at home and abroad. We welcome new and old customers to come to consult & negotiate with us. Your satisfaction is our motivation! Let us work together to write a brilliant new chapter! We are now looking forward to even greater cooperation with overseas customers based on mutual benefits. We will work wholeheartedly to improve our products and services. We also promise to work jointly with business partners to elevate our cooperation to a higher level and share success together. Warmly welcome you to visit our factory sincerely.