DF40C-10DP-0.4V(51) from Hirose Electric Co Ltd is a fine-pitch rectangular mezzanine board-to-board connector designed for compact electronic assemblies where space, profile, and interconnect reliability are critical. As a 10-position, 2-row surface-mount plug with outer shroud contacts and solder retention, it is well suited for portable devices, industrial control boards, embedded modules, communication equipment, and other dense PCB designs that require precise stacking options. The DF40C family is commonly selected by engineers for compact signal interconnects in low-profile applications, supported here by multiple mated stacking height options. Based on the provided specifications, the part is RoHS compliant and REACH unaffected, which supports use in environmentally regulated markets and new design programs. Lifecycle status is listed as unknown, so procurement teams should verify current manufacturer status before locking it into long-term production. For ongoing builds, engineers should confirm latest availability, documentation, and compliance records through authorized sourcing channels and official Hirose references.