Westinghouse 6 Pack Pagoda II Black Solar Post Cap Lights for 4 x 4 Wood Posts Interior base measures 3.88" x 3.88", rail adapter interior measures 3.5" x 3.5".Each light measures 5.94" x 5.94" x 4.75" Durable weather resistant plastic construction will handle the outdoors with ease Bright white LED bulb is powered by the included 600mAh Ni-Cd battery Solar panels will absorb sunlight regardless of cloud cover Includes mounting base for installing onto a rail