1. Keys. (1) there is no rust on its surface. If rust, indicating no plating is good, (2),stiffness, poor quality, can be broken with your hands bent or broken.
2. The lock casing. (1) no cracks on its surface. If so, note shell injection-locked-doped. (2) gently pinch, would burst.
3. See the cables (1) there is no leakage of wire and carefully handle. (2) see the cable thickness, thicker description the stronger.