DF40HC(3.0)-70DS-0.4V(51) from Hirose Electric Co Ltd is a fine-pitch rectangular board-to-board receptacle designed for compact, high-density electronic assemblies. With 70 positions, 0.40 mm pitch, dual-row construction, and 3 mm mated stacking height, it fits applications where signal routing density and low-profile interconnect design are critical, such as portable devices, industrial control modules, embedded computing, and communication equipment. The SMT mounting format and tape-and-reel packaging also support automated volume assembly. Based on the provided data, the part is listed as Active with sufficient supply status, which is favorable for ongoing procurement, although engineers should still confirm long-term availability directly with the manufacturer for new designs. RoHS compliance information is not explicitly provided in the supplied specifications, so compliance status should be treated as information not available until verified through official Hirose documentation or manufacturer-issued material declarations. This part is best positioned for designers needing a compact, reputable interconnect solution from an established connector supplier.