A humane and safe way to moles, gophers, groundhogs, voles and other burrowing rodents, they are chased away unharmed. No chemicals or Extensive Coverage: Operates in a circular pattern, approximately 40 ft. in diameter. So it is recommended to use 12 solar mole repeller units per acre. Weatherproof Solar Mole Chaser Spikes: pulses emitted 3s pulses for every 30s, it penetrates the soil for and forces to evacuate the area covered by the sound. .Solar-Powered Mole Deterrent: This Mole chaser spike are charged by its solar panel. 4-hour solar charge lasts for 5 days working, no need to replace battery. In general, it need about 2-4 weeks to drive the Mole & away from your garden, Then your garden be free of these nuisance critters after some weeks