Give little pets supportive feeds with the Hartz Nursing Bottle. It s specially designed to aid in nourishing newborn animals providing an accurate way to measure appropriate formula amounts that need to stay precise for each little one. Each bottle set includes an elongated rubber nipple that fits inside the cap-ring and twists onto the top of the 2 oz plastic pet bottle. Each new nipple is initially closed and doesn t allow for fluid transfer. The nipple needs to be punctured before use to establish flow. By changing the width of the piercing the flow can be increased for growing pet needs.