The 5811 Series Board-to-Board connector is optimized for small devices such as wearable devices. It is miniaturized to 1.7 mm in width. Moreover, it maintains durability by adopting a flat stacking structure which enables workability when stacking and reduction of damage despite its low 0.6mm stack height. In addition, it is also resistant to the high current required for connectors which is suitable design for battery connection.