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. Overall, Japan, the US and Europe each have their strengths in crowned tooth and gear couplings: Japan excels in tooth crowning and consistency, the US in high-torque grading and durability, and Europe in integrated design and sealing. The domestic GICL series, however, holds clear advantages in cost-performance, lead time and spare-part convenience, meeting most medium-to-heavy duty conditions. Sealing and lubrication are critical to coupling life. Domestic GICL commonly uses lip seals with lithium grease—simple and easy to maintain; European products often adopt labyrinth seals with centralized lubrication interfaces, better suited to long-running, low-maintenance automated lines. Understanding the differences between domestic and foreign crowned tooth couplings helps make better decisions in equipment matching and retrofit. It is recommended to perform selection calculations for the specific duty and consult professional manufacturers when necessary.