DF37NC-40DS-0.4V(51) from Hirose Electric Co Ltd is a fine-pitch rectangular receptacle connector designed for compact board-to-board interconnect applications where height, density, and assembly efficiency are critical. With 40 positions, 0.40 mm pitch, dual-row layout, and surface-mount mounting, it fits space-constrained designs such as portable electronics, industrial control modules, compact embedded systems, and display or communication subassemblies. Engineers typically select this DF37 family part for reliable signal interconnection in low-profile layouts that require precise mating geometry and automated reel-based assembly. From a sourcing perspective, this component deserves planning attention: the provided data shows limited supply status and an estimated EOL date of 2025, while official lifecycle status remains unknown. RoHS compliance information is not explicitly provided in the supplied specifications, so compliance should be treated as information not available until verified through the manufacturer datasheet or formal compliance documentation.