said first yarns and said second yarns being interknitted to form a plurality of holes extending through said first and second surfaces, and to have first portions of said first coating layers of said first yarns and first portions of said second yarns forming said first surface, and second portions of said first coating layers of said first yarns and second portions of said second yarns forming said second surface, said first portions of said first coating layers at said first surface being larger in surface area than said second portions of said first coating layers at said second surface; and a fabric layer disposed on said second surface of said mesh covering unit.