Container closure

1. A container closure for sealing against an outer surface of a rim of a container comprising:

a substantially disk shaped member formed as a solid piece with no openings and comprising:

a top wall;

a circumferential rim extending about a periphery of the top wall, the circumferential rim including an outer side annular wall, wherein the outer side annular wall has a top edge portion and a bottom edge portion flared outwards from the top edge portion; and

a plurality of indentations in the outer side annular wall at different circumferential positions of the outer wall and at a same vertical position of the outer wall, forming a plurality of ribs each having a generally curved profile protruding convex profile that protrude directly toward a center of the substantially disk shaped member;

the top wall comprising:

a central circular horizontal portion or a central circular concave portion that is depressible by a user so as to push the plurality of indentations in the outer side annular wall of the substantially disk shaped member down past an outer surface of a rim of a container when the container closure is centered on top of the container and so that the container closure seals against the outer surface of the rim of the container, with an upper surface of the plurality of indentations touching against the lower portion of the outer surface of the rim when sealed; and

a ring structure disposed between (a) the central circular horizontal portion or the central circular concave portion, and (b) the periphery of the top wall, the ring structure set into the top wall and sunken relative to both the central circular horizontal portion or central circular concave portion, and sunken relative to the periphery of the top wall, the ring structure comprising:

a plurality of radial spokes raised relative to a bottom portion of the ring structure, the bottom portion of the ring structure comprising

flat horizontal portions in between each pair of adjacent radial spokes.

2. The container closure of claim 1 , wherein the container closure comprises polypropylene.

3. The container closure of claim 1 , wherein the entire container closure is formed as a single piece of polypropylene.

4. The container closure of claim 1 , wherein the container closure does not comprise High Impact Polystyrene (HIPS) or Polyethylene Terephthalate (PET).

5. The container closure of claim 1 , wherein the container closure comprises a central circular concave portion.

6. The container closure of claim 1 , wherein the concave portion is a concave disc.

7. The container closure of claim 1 , wherein the container closure comprises a central circular horizontal portion.

8. The container closure of claim 1 , wherein the plurality of radial spokes are rectangular shaped.