Abstract: A barrier includes a frame and a gate engaged within the frame, the barrier has a first state and a second state, a length of the frame in the second state being smaller than that in the first state, and a length of the gate in the second state being smaller than that in the first state.

Abstract: The present invention discloses a two-layer pet waterer. The two-layer pet waterer comprises a water tank and a first drinking plate arranged above the water tank, and a fountain opening is connected with the bottom of the first drinking plate. The fountain opening is connected with a water pipe, and the water pipe is connected with a low-water-level pump. A second drinking plate is arranged below the first drinking plate. The low-water-level pump pumps water into the first drinking plate, and after the water is full of the first drinking plate, it leaks into the second drinking plate. A pet can choose the first drinking plate or the second drinking plate by itself to drink the water.