Covers up to 9000 sq.ft. about 836 sq. metres Battery operated batteries normally last for around 4 months. Safe & economical to run. Environmentally friendly no chemicals or traps. Will not affect humans cats dogs fish or birds Requires 4 D size batteries An advanced sonic repeller that drives burrowing animals away by emitting low frequency ground vibrations which creatures such as moles interpret as signs of an approaching intruder. The unit emits a low frequency vibration every 15 to 20 seconds which is transmitted through the soil. The effectiveness of the mole repeller can be affected by soil density chalky or sandy soil will not transmit the vibrations as effectively as solid clay-type soil. To increase saturation additional units are advised to create a low frequency barrier.