The mark consists of a three-dimensional configuration of a cylinder comprising a transparent outer cylinder and a non-transparent ring that delineates the upper and lower portion of the transparent outer cylinder. The upper portion of the transparent cylinder contains an inner non-transparent cap that extends upwards from the non-transparent ring, forming an empty space between the top inner surface of the upper portion of the transparent cylinder and the top outer surface of the inner non-transparent cap. The lower portion of the transparent cylinder has an inner surface forming a cavity that contains an inner non-transparent tub that extends downward from the non-transparent ring, forming an empty space between the bottom surface of the lower portion of the transparent cylinder and the bottom surface of the inner non-transparent tub. The lower portion of the transparent cylinder gently tapers down to form a slightly smaller diameter at the bottom of the lower portion of the transparent cylinder. The plurality of long, broken, parallel lines shown closely together are not part of the mark and serve only to show the shading, position, or placement of the mark.