The ornamental design for a narrow lower fencerailrestrainer, as shown and described.
FIG. 1 is a top view of a narrow lower fence rail restrainer showing my new design;
FIG. 2 is a left side view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a right side view thereof; and,
FIG. 5 is a bottom view thereof;
FIG. 6 is a back view thereof; and,
FIG. 7 is an isometric view thereof.
FIG. 8 is an environmental view thereof restraining a chain link fence to the ground. The chain link fence and ground shown in dashed lines are for illustrative purposes only and do not form part of the claimed design.