Keep Moles and Gophers Out of Your Yard with P3 International Sonic Mole Chaser Stakes Box of four P7900 Sonic Molechaser R from P3 International. A humane and environmentally friendly way to minimize damage to gardens and lawns from moles, voles, shrews, gophers and other destructive ground rodents. P7900 Sonic Molechaser R operates in a circular pattern, about 120 ft. in diameter. Must be unobstructed 120 ft. Coverage about 1/4 acre in most soils. Range of effectiveness depends upon soil type. Harder, packed soils conduct sound waves farther than dry, sandy, or peat soil. Install Molechasesr R at site of the worst rodent infestation. Remove Sonic Molechaser R if ground freezes or when flooding occurs. Each is made from a single billet of aluminum 16 inches long, 2 inch diameter. Green cap. 14 ounce weight empty. Approved by consumer groups tested by a U.S. certified laboratory. Each sonic Molechaser R produces a penetrating underground sonic pulse of 300 Hz at 15 second intervals, covering up to 11,250 square feet 1/4 acre . Pets aren't affected rodents find the noise irritating and move to quieter surroundings. Green control head is watertight bury flush with lawn surface for easy mowing. Change batteries without removing unit from ground pull out battery cylinder. Uses 4 D cells not included . 6VDC. Battery life 4-6 months. 100% waterproof. 16 inches long by 2 inches in diameter. Weight 11.5 ounces. Limited Lifetime Manufacturer's Warranty. NOTE Do not expect instant results. Usually, continuous usage for 7 to 14 days is needed before effective at gopher control or other rodent control. Initially, the Mole Chaser can cause increased pest activity. Initially, the pests mistake currents as food source and leave when they realize the currents are not food. Make sure earth is firmly packed around each stake. Do not pound into ground loosen or wet soil and push into ground. Then pack soil tightly around each unit.