In heavy equipment, crowned tooth gear couplings are widely adopted for their high load capacity and strong misalignment compensation. After decades of technical accumulation, China has built a complete product system covering design, machining and inspection, gradually narrowing the gap with advanced foreign products. American gear couplings are based on AGMA standards; brands such as Falk, Lovejoy and Kop-Flex have deep influence in mining, energy and marine fields. AGMA products emphasize clear grading of rated torque and allowable speed, with structures biased toward durability and serviceability. Compared with domestic GICL, AGMA gear couplings offer richer choices in extra-high torque and special bore specifications. Crowning of the tooth tip directly affects contact stress distribution. Domestic makers widely use CNC machining for tooth-form accuracy, while foreign makers have deeper know-how in optimizing the crowning curve and suppressing edge contact, helping reduce local stress concentration and abnormal noise. In summary, domestic crowned tooth couplings already have the technical basis to replace imports; users can select reasonably based on duty, budget and lead time. We will keep sharing selection and maintenance essentials for the GICL series.