Use this piece to hang and secure a canvas, a picture, ... to the wall. Fix this piece to the canvas/picture with 2 screws. Then fix a big screw in the wall. Then position the canvas/picture so that the big screw is inserted and slided in this piece.

Use a screw that has a head between 5 mm and 10 mm, with a body thinner than 4 mm.

-The round hole is 10 mm wide.
-The slider is 4 mm wide.
-The two holes for fixing are 4 mm wide.

Enjoy.
Julien