DF40C-80DS-0.4V(51) from Hirose Electric Co Ltd is a fine-pitch rectangular board-to-board receptacle designed for compact electronic assemblies that require high contact density and reliable SMT mounting. With 80 positions in a 0.40 mm pitch, two-row format and a low-profile 1.5 mm mated stacking height, it fits space-constrained products such as portable devices, industrial control modules, embedded computing hardware, and display or communication subassemblies. Engineers typically select parts in this connector class when signal routing density, low board height, and stable mechanical interconnect performance are priorities. The provided status indicates Active, which is favorable for ongoing production planning, although the broader lifecycle field is listed as unknown and should still be confirmed through Hirose documentation. RoHS compliance information is not explicitly provided in the supplied specifications, so compliance status should be treated as information not available pending official manufacturer confirmation or datasheet review.