Solar Power Square LED Fence Post Light for 4x4 PVC Posts (Wood Grain) Fun faux brown wood finish Rechargeable Battery included (AA Ni-Cd) 100% Solar Powered no external wiring necessary 1 White LED Per Light, 2.5 Lumens The opening on the bottom of this light, which fits over the top of your PVC post, is exactly 4 1/16" x 4 1/16".