Add some light and style to your posts with this 8 Pack of Solar Powered LED Post Lights by GardenSunlight. These versatile post caps can be used on your patio, deck, fence, or pathway. The included 1.2V 600mAh AA Ni-CD battery will be recharged every time the solar panel absorbs sun light. These lights feature a unique mechanism that allows you to turn it on once and never have to worry again. No additional wires or power source are needed. It is recommended to install these post cap lights in an area that receives sunlight for 6 to 8 hours a day. Product Dimensions - 5.75" x 5.75" x 4.5", Base Dimensions: 4" x 4" Nominal Wood Post Size Fitting; these post caps will ONLY fit on nominal 4" x 4" wood posts (actually measures 3.63" x 3.63". The opening on the bottom of the post cap which fits over the top of the post is exactly 3 7/8" x 3 7/8*** This post cap is not designed for use on Plastic, PVC, or Vinyl posts!