a resilient contact piece having a plurality of small dots on the surfaces thereof. [0032]FIGS. 5A, 5B and 5C are perspective views showing other examples of a resilient contact piece having a plurality of small elongated dots on the surfaces thereof. [0033]FIGS. 6A and 6B are a plan view and a side view showing an example of a resilient contact piece having projections on both sides of the distal