This is a water bottle for walking pets. I bought it for my micro pig, but it couldn't be used due to the length of its snout, and I haven't used it at all after putting water in it once. The mechanism is such that water comes out when the button is pressed while the bottle is lying down, and the water can be returned when the button is pressed while it's upright. The button can also be locked by sliding it. It holds 300ml of water.