The ornamental design for a containertoprail, as shown and described.
FIG. 1 is a perspective view of a container top rail showing the subject design;
FIG. 2 is a front view of the container top rail shown in FIG. 1;
FIG. 3 is a top view of the container top rail shown in FIG. 1;
FIG. 4 is a side view of the container top rail shown in FIG. 1; and,
FIG. 5 is a perspective view of the container top rail shown in FIG. 1.
The container top rail is shown with symbolic breaks in its length. The appearance of any portion of the article between the break lines form no part of the claimed design. The broken lines showing a container in FIG. 5 are for the purpose of illustrating environment and form no part of the claimed design.