Sweeney's S7906 Sonic Spike PRO Repellents with Hyper Pulse Technology Moles, gophers and other burrowing animals are chased away unharmed Convenient, removable battery chamber Sonic pulses and vibration emitted every 18 seconds Each spike covers up to 13,500 sq. Feet (1/3 acre) Operates in a circular pattern, approximately 130 ft. In diameter