A module fitting design: improved user’s convenience with a minimum size and thickness, using a shape of the internal module and removing all other spaces except the module space. Pentagonal module fitting design makes a differentiation, and a round processing to the side improves user’s feeling of grip and satisfaction. 3D pattern: soft 3D pattern gives a sense of visual softness and elegance. 3D CAD cannot easily express this pattern. It can be finished in an injection state without additional post processing. Therefore production is eco-friendly and the quality of the product appearance can be improved.