The ornamental design for a border for mattresses, as shown and described.
FIG. 1 is a perspective view of a border for mattresses showing my new design.
FIG. 2 is a left elevation view of the border for mattresses of FIG. 1.
FIG. 3 is a right elevation view of the border for mattresses of FIG. 1.
FIG. 4 is a rear elevation view of the border for mattresses of FIG. 1.
FIG. 5 is a front elevation view of the border for mattresses of FIG. 1.
FIG. 6 is a top plan view of the border for mattresses of FIG. 1, which is identical to the opposite, bottom plan view of the border for mattresses of FIG. 1; and,
FIG. 7 is an enlarged view of a corner of the border for mattresses and is illustrative of a portion of each of FIGS. 1-5 showing the design shown in closer detail.
The broken lines shown in the drawings are for environmental purposes only and form no part of the claimed design. The areas encompassed by the broken lines form no part of the claimed design.