4mm Jamb Cleat
Burgee brand.
Black nylon. 
4 mm diameter cord or rope capacity.  Feed the cord/rope through a hole in the back of the cleat.
Size: 66mm long x 12mm wide by 16mm high. Mounting hole centres: 54mm.

This product is also ideal for safely securing picture frames to the wall.  As used by art galleries. 
Screw two cleats to the wall ("V" opening to the top) and fix two 6 gauge screws to the back of the frame leaving the screw heads protruding approximately 4mm.  Place frame in position on the wall and lower the two screw heads into the "V"s.