DF40C-50DP-0.4V(51) from Hirose Electric Co Ltd is a 50-position rectangular board-to-board connector plug designed for compact, high-density interconnect applications. With a 0.40 mm pitch, dual-row layout, SMT mounting, gold-plated contacts, and multiple supported stacking heights, it is well suited for portable electronics, industrial control modules, embedded systems, and other space-constrained assemblies where reliable signal transfer and low-profile design are important. Engineers typically select this series for fine-pitch board stacking, mechanical stability, and efficient PCB space utilization. Based on the provided specifications, the part is listed as Active, which supports use in ongoing production designs, although lifecycle confirmation should still be verified with Hirose or an authorized source. RoHS compliance information is not explicitly provided in the input data, so compliance status should be treated as information not available until confirmed through the official datasheet, manufacturer declaration, or distributor compliance documentation.