We bought this to use to feed our two adult cats whenever we go out of town for a few days. We chose this model because it was reasonably priced and holds enough food for up to six days. The unit has six pie-shaped (wedge) sections that you fill with food; one section is always exposed, so it basically holds food for today plus five more servings. There is a switch that lets you select between 6, 12, or 24-hour serving intervals. At the preset interval, the lid advances to the next section. Each section holds enough dry food forup to two cats if you fill them up. There is no clock display on the unit; there is a manual "advance" button on the unit; whenever you press this, the lid rotates to the next opening and it resets the timer so that it will advance at the preset interval after this, or it will advance at the preset interval after you install the battery (one 9-volt Alkaline battery). There are some small water tanks on the botton that are intended to be filled with water and frozen to keep canned food cold, but they are useless after more than a few hours. Overall, the unit does what it is supposed to do very well, without any complicated clock or timer settings to worry about, and it is large enough to hold a few days worth of food.