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.1. Adhering to the principle of "Enterprising and Truth-Seeking, Preciseness and Unity", with technology as the core, our company continues to innovate, dedicated to providing you with the highest cost-effective products and meticulous after-sales service. We firmly believe that: we are outstanding as we are specialized. 2. With all these supports, we can serve every customer with quality product and timely shipping with highly responsibility. Being a young growing company, we might not the best, but we are trying our best to be your good partner. 3. We warmly welcome domestic and overseas customers to visit our company and have business talk. Our company always insists on the principle of "good quality, reasonable price, the first-class service". We are willing to build long-term, friendly and mutually beneficial cooperation with you.