Crowned tooth couplings replace straight teeth with crowned teeth, distributing meshing contact more evenly along the tooth width and thereby improving load capacity and fatigue life. Domestic products follow GB/T crowned tooth coupling standards, differing from foreign products in structure and parameter systems. European couplings are represented by Germany's KTR, Flender, Renold and Voith, following the DIN/ISO system. European products are mature in sealing, lubrication and anti-corrosion, with high modularity and integration. Compared with domestic GICL series, European designs excel at integrated coupling with gearboxes and brake discs, performing stably under continuous operation. Selection should integrate operating torque, peak load, allowable speed and compensation capacity. The domestic GICL series covers nominal torque roughly Tn 630~450000 N·m, satisfying most medium-to-heavy scenarios; for extreme conditions (high temperature, strong corrosion, extra-long span), imported or custom solutions may be referenced. 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.