Abstract: The door handle contains a positioning element, an engaging ring, and a handle member. The positioning element is flat and substantially rectangular with four rounded corners. Four notches are formed besides the four corners, respectively. The inner circumference of the engaging ring is divided equally into four arc sections, each having a J-shaped track. Along the outer circumference of the engaging ring, a curved slot where an elastic plate is embedded and a neighboring axial groove are provided. After the positioning element is fixed to a lock on a door, the engaging ring and a first cover of the handle member are sleeved over the positioning element. By twisting the first cover which in turn rotates the engaging ring, the four corners follow the J-shaped tracks and are thus locked and the elastic plate is embedded into one of the notches.

Abstract: The locking device contains an axle, a bolt, a positioning plate, and a cylinder. The axle is connected to a thumb-turn knob and, from a circumference of the axle, a lever is extended perpendicularly. The bolt has a vertical trough in a rear section. An end of the lever is embedded in the trough. The positioning plate has an elongated opening inside which the axle is embedded. The cylinder is positioned adjacent to and above the rear section of the bolt. The cylinder has a key hole in the center and an activation bar extended from a circumference of the cylinder. When the thumb-turn knob or a key in the key hole is turned, the positioning plate is moved towards an opposite direction. In turn, the lever of the axle pushes or pulls the bolt in the same directions as the key or the knob is turned.

Abstract: The door handle contains a positioning element, an engaging ring, and a handle member. The positioning element is flat and substantially rectangular with four rounded corners. Four notches are formed besides the four corners, respectively. The inner circumference of the engaging ring is divided equally into four arc sections, each having a J-shaped track. Along the outer circumference of the engaging ring, a curved slot where an elastic plate is embedded and a neighboring axial groove are provided. After the positioning element is fixed to a lock on a door, the engaging ring and a first cover of the handle member are sleeved over the positioning element. By twisting the first cover which in turn rotates the engaging ring, the four corners follow the J-shaped tracks and are thus locked and the elastic plate is embedded into one of the notches.

Abstract: The locking device contains an axle, a bolt, a positioning plate, and a cylinder. The axle is connected to a thumb-turn knob and, from a circumference of the axle, a lever is extended perpendicularly. The bolt has a vertical trough in a rear section. An end of the lever is embedded in the trough. The positioning plate has an elongated opening inside which the axle is embedded. The cylinder is positioned adjacent to and above the rear section of the bolt. The cylinder has a key hole in the center and an activation bar extended from a circumference of the cylinder. When the thumb-turn knob or a key in the key hole is turned, the positioning plate is moved towards an opposite direction. In turn, the lever of the axle pushes or pulls the bolt in the same directions as the key or the knob is turned.