Disclosed is a bi-directional differential pressure flow sensor that is configured to establish a direction and flow rate of a fluid flow. A water-absorbing agent made of water-absorbing resin powder is accommodated in the guide member toward the one end. The method also includes sealing the media within one end of the seed shell, depositing an embryo within the seed shell, and sealing the embryo within the seed shell. The tab press which forms the lift tabs in the stock material is capable of receiving strips of stock material having varying widths.