DF40C(2.0)-20DS-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 a 0.40 mm pitch, 20 positions, dual-row layout, and 2 mm mated stacking height, it is well suited for space-constrained products such as portable devices, industrial control modules, embedded computing platforms, and communication equipment. Engineers typically select this series when they need reliable SMT interconnect performance, low-profile board stacking, and a proven connector platform from an established manufacturer. The supplied status indicates Active, which is favorable for ongoing designs, although the broader lifecycle field is listed as unknown and should still be verified through current manufacturer documentation before long-term commitment. RoHS compliance information is not explicitly provided in the supplied specifications, so compliance should be treated as information not available pending confirmation from Hirose or an authorized source. For procurement teams, balanced supply-demand conditions are a positive sign, but counterfeit exposure in the open market reinforces the value of sourcing through trusted channels.