The ornamental design for the vial holder element, as shown and described.
FIG. 1 is a top plan view of the vial holder element in accordance with the present invention;
FIG. 2 is a bottom plan view of the vial holder element thereof;
FIG. 3 is a rear elevation view of the vial holder element thereof;
FIG. 4 is a front elevation view of the vial holder element thereof;
FIG. 5 is a right side elevation view of the vial holder element thereof;
FIG. 6 is a left side elevation view of the vial holder element thereof;
FIG. 7 is a lower right exploded perspective view of the vial holder element thereof; and,
FIG. 8 is a perspective view of a plurality of the vial holder elements thereof shown in the vial holder configuration.
The broken lines in the drawings showing the additional vial holder elements and vials in FIG. 8 are for illustrative purposes only and form no part of the claimed ornamental design. The broken lines in the drawings showing the order of assembly of the exploded view in FIG. 7 are for illustrative purposes only and form no part of the claimed ornamental design. The remaining broken lines in FIGS. 1-8 are directed to portions of the vial holder element that are not considered part of the claimed ornamental design. None of the broken lines form a part of the claimed design.