Sweeney's S7900 Heavy Duty Sonic Spike Repellents Moles, gophers and other burrowing animals are chased away unharmed Convenient, removable battery chamber (batteries not included) Sonic pulses emitted every 15 seconds Each spike cover up to 11,250 sq. Feet (1/4 acre) Operates in a circular pattern, approximately 120 ft. In diameter