During the day, these energy-efficient Atlantic Solars™ lights harness sunlight energy to charge their internal Lithium Battery. At night they automatically turn on, emitting a bright glow for your fence post line. Each Atlantic Solars™ light is made of Premium Heat-Resistant Plastic for years of use. With our Newest & Improved Solar Panels, a 3.2V Lithium Ion Battery, and 5 Ultra Bright White LEDs, its output is virtually unparalleled. • Atlantic Solars™ 4″x 4″ Fence Post Caps • One Pre-Installed 3.2V Lithium-Ion Battery for each light • Light source: 5 Ultra Bright LEDs • Solar panel: New & Improved For Superior Charging • Material: Premium Heat-Resistant Plastic • Operating Time: Up to 10 Hours (depending on weather, sunlight availability) • Safe & Weather Resistant with CE Certified LED Light Bulbs • Dimensions : 5.4″ (L) X 5.4″ (W) X 3.5″ (H) • Mounting Bases(Inside Diameter): 3.75″ X 3.75″ (Solid Wooden/Composite Post)