The M20-7852042 is a 40-contact 2.54mm female DIL Board-to-board Socket with gold plated phosphor bronze contacts, 100% tin over nickel plated termination and black UL94V-0 polyamide (nylon) 6T housing. The M20 series receptacle has 3mm PC solder tails, vertical connector orientation, PC tail/through board connection type and dual entry style (bottom entry, top entry). It is suitable for use with 0.64mm square mating pin size. Suitable for interconnecting board to board. The socket is a box section design with a latch to locate and hold in an insulated housing.