Solar light for capping fence posts，solar post lights 3x3，solar post cap lights 4x4 Ideal for 3 x 3, 4 x 4 inch posts Without base: 3 x 3 inch posts is just right With base: 4 x 4 inch postsn is just right Comes with mounting kit for posts，If the post diameter size is smaller or larger than this sizes，you can use the included the screws fix the bracket on the post top,then buckle the lamp directly. (Note: 5X5 6X6 inches size requires solid wooden posts).