User-Friendly Screw-on bracket: Simple and Easy Installation. You can easily snap the water Bottle on or off for cleaning and refilling water. Nail-on bracket: It may also be nailed to the wall or wooden furniture with screws. Simple and easy use for inside or outside cage. Ripple-wall design of interior panel, anti-skid and sturdy struct ion. Pet owner can switch our bottle to most regular sized PET bottles Important Instruction: Please tap the nozzle tip after refilling the water bottle to ensure water is coming out. Air bubbles will be shown when you are tapping the nozzle tip and the water bottle is ready to use.