Instillation container with level-difference portion

An eyedropper, comprising:

• a one piece plastic container having a seamless outer surface characteristic of blow-molding or vacuum-molding a one piece container, the container having a closed end, an instilling arrangement at the opposite end and external threads between the closed end and the instilling arrangement, of the container;
• the instilling arrangement comprising:
• a step having a step portion and a first tubular member, wherein the surface of the step portion faces away from the closed end of the container and the first tubular member has an external, generally conical convex surface;
• a second tubular member between the external threads and the step portion of the step, wherein the step is on an outer surface of the instilling arrangement and the outer surface of the second tubular member is an outer convex surface;
• a third tubular member connected to the first tubular member, wherein the juncture of the first and the third tubular members provides an exterior opening and the external, generally conical convex surface of the first member tapers to the exterior opening, the third tubular member extending away from the exterior opening into the second tubular member with end of the third tubular member spaced from the exterior opening providing an interior opening, wherein the third tubular member has an internal, generally conical concave portion that tapers to the interior opening and the third tubular member provides a fluid passageway from interior of the container to exterior of the container when the exterior and interior openings are open;
• and a cap, comprising:
• a body having a closed end, an opposite open end and internal threads, the interior of the body of the cap sized for the open end and body of the cap to move over the instilling arrangement of the container, and interior surface of the cap configured to provide a convex guide portion extending toward the open end of the cap and circumscribing internal portions of the cap, wherein the outer convex surface of the second tubular member guides the cap when the cap is mounted over the instilling arrangement, and with the cap over the instilling arrangement the internal portions of the cap are in sealing communication with the exterior opening to provide a first seal, and in surface contact with the surface of the step portion to provide a second seal, and the convex guide portion of the body of the cap contacts the outer surface of the second tubular member to guide the cap over the instilling arrangement.