Using a French cleat to mount pictures, shelves and other wall-mounted items is a great idea, because it hides the fixing and is easy to remove when it is not needed. The idea behind this kind of fixing is simple, and easy to use in almost all situations. Some stores sell French cleat fixings in strong materials such as aluminum to add a little extra sturdiness to the fixing.
What is a French cleat fixing?
The fixing looks like two angled pieces of material that, when slotted together, look like one solid piece that has been slit diagonally down the middle. The French cleat works because the top piece that is affixed to the shelf or photo slots diagonally into the piece which is secured to the wall, and gravity ensures that it does not fall out or become unstuck. No glue or screws are needed to reinforce this fixing, other than those used to affix each piece to the wall or item to be mounted.