Westinghouse Solar 20 Lumens 4x4 Post Light for Wood Posts (Black, 4 Pack) Mounts to standard 4 x 4 wood posts. Posts actually measure 3.63" x 3.63" Automatically turns off and on with the onset of nightfall Bright LED light produces a 20 Lumens output for 6 hours before dimming to 5 Lumens for the remainder of the night Each light includes 1 x 3.7V 1000mAh 18500 Li-Ion battery and 1 x base adapter for rails Each light measures 5.91" x 5.91"