C: Style (Without reinforcing metal fitting); 90: Number of Positions; DS: Connector Type (Receptacle); 0.4V: Contact Pitch (0.4mm) and Plating (Gold Plating). (51): Packaging (Embossed tape packaging). Series Name: 0.4mm Pitch, 1.5 to 4.0mm Height, Board-to-Board/FPC-to-Board Connector.