Saim Battery-Operated Automatic Fish Feeder Ideal for various sizes of aquariums with two options of placing the food feeder on aquarium, free-standing or rim-mounted Power Source: 2 AA 1.5V alkaline batteries (NOT INCLUDED) Measurements: approx. 11cm/4.3" (H) x10cm/3.9" (L) Drum: diam. -C 6.5cm/2.6"; height -C 2.7cm/1.1" Fish Feeding times can be set to once or twice daily, feeding drum is ideal for flakes or granulates