The NuTone haven backyard mosquito repellent system produces an invisible zone of protection which repels biting mosquitoes. Each mosquito repellent fixture contains a vaporizer that releases an odorless, invisible repellent that protects a 12 ft diameter area. Use repellent fixture on a deck, patio or outdoor area for up to 440 sq-ft of coverage. You can add a fixture for 110 sq-ft of additional protection. The kit includes: 4 fixtures, 4 repellent cartridges, 65-feet low-voltage wire, 1 controller. For use with NuTone Haven expander kit HVRBRKTCX. Effective protection against all types of mosquitoes. Over 216 hours of mosquito protection per each repellent cartridges. Provides protection within 15 minutes. Durable construction. Install only once, enjoy season after season. 3-year limited warranty. For use with HVRBRKTCX to cover up to 550 sq-ft.