Years ago I needed extra pegs for the perimeter wire of a robotic mower.
Ever since I've used these pegs for similar applications outside.

Due to the rounded and filleted wire channel they're specifically suited to secure electric (perimeter) wires but they should be also usable for any other type of wire or cord.

I've added both the straight and the barbed versions.

Note: as usual, the stereo images are of the cross-eyed type.