4x4 Solar deck lights (aka solar post caps) for wood posts measuring 3-1/2" x 3-1/2" are very easy to install and will add the perfect finishing touch to your deck, fence, gate, sign, mail or dock posts. Choose from a wide selection of decorative solar powered post caps in luxurious copper, classic white, sleek black, designer glass and more.  Just install in a sunny location for auto dusk to dawn lighting.