With the Oasis Self Watering System you do not have to worry about watering your plants when away from home. The Oasis has 4 independent watering programs: 10-20-30-40 days that can be selected by simply turning the dial to water a maximum of 20 plants. LED light located on programming panel indicates when unit is in use or when battery is low. Isolated tank prevents condensation and non-slip rubber feet avoids scratching of surface or sliding of tank. Operates on one 9v battery (not included). Gravity feed. No pump. Unit dimensions is 15 in x 15 in x 15 in & 9.5 lb.