1.) Z-Hanger & T-Screw Security Hardware: --
The Z-Hanger + T-Screw Security Hardware for Wood Frames and Gallery Wrapped Canvas pieces is the best way to hang and secure wood framed and gallery wrapped canvas pieces. The Z-Hanger latches into a wall-attached z-hanger (included) and allows the piece to hang squarely and easily slide left-to-right to get the distribution of space between pieces exactly right. It is also a fixed distance from the top-line of the frame, making it easy to hang pieces side by side by side while staying on the same straight line.
If you choose to install the T-Screw cleat at the bottom, your piece will be permanently affixed to the wall, making it nearly impossible to take/steal without the T-Screw's wrench (pictured, and included). The T-Screw slots into the cleat sideways, and the wrench twists the T-Screw head 90°, perpendicular to the direction of the cleat, effectively locking the artwork to the wall.