The ornamental design for a containerinsert, as shown and described.
FIG. 1 is a front, top isometric view of a container insert showing our new design;
FIG. 2 is a front elevational view of the container insert of FIG. 1;
FIG. 3 is a rear elevational view of the container insert of FIG. 1;
FIG. 4 is a right side view of the container insert of FIG. 1;
FIG. 5 is a left side view of the container insert of FIG. 1;
FIG. 6 is a top plan view of the container insert of FIG. 1;
FIG. 7 is a bottom plan view of the container insert of FIG. 1;
FIG. 8 is a rear, bottom isometric view of the container insert of FIG. 1;
FIG. 9 is a front, top isometric view of the container insert of FIG. 1, shown with environmental subject matter; and,
FIG. 10 is an exploded front, top isometric view of the container insert of FIG. 1.
The broken-line showing of a bowl in FIGS. 9 and 10 illustrates environmental structure which forms no part of the claimed design. All other broken lines in FIGS. 1-10 represent anti-nesting portions of the container insert which are environmental and form no part of the claimed design.