DF37B-20DP-0.4V(51) from Hirose Electric Co Ltd is a fine-pitch rectangular board-to-board connector designed for compact electronic assemblies where low profile, secure SMT mounting, and reliable signal interconnection are critical. With a 0.40 mm pitch, 20 positions, dual-row layout, and gold-plated contacts, it fits high-density applications such as portable devices, industrial control modules, embedded boards, medical electronics, and space-constrained consumer products. Features such as solder retention and a reel packaging format support automated assembly and stable production handling. Based on the provided data, this part is listed as Active and current supply status is noted as sufficient, which is helpful for ongoing production programs and maintenance purchasing. RoHS compliance information is not explicitly provided in the supplied specifications, so compliance status should be treated as information not available until confirmed through official Hirose documentation or manufacturer-backed distributor records. For engineering teams, this connector is positioned as a compact, production-oriented interconnect option for modern high-density PCB designs.