The ornamental design for a stairtrackrail, as shown and described.
FIG. 1 is a left perspective view of a stair track rail showing the new design;
FIG. 2 is a top view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is another left perspective view of of the stair track rail shown in an environment of use; and,
FIG. 5 is a left perspective view of the stair track rail of FIG. 1, with the broken line portions of the stair track trail removed to show aspects of the design that may not be apparent in the other views.
The broken lines shown on the rail in the drawings depict portions of the stair track rail that form no part of the claimed design. All other broken lines depict environment and form no part of the claimed design.