GreenLighting Solar LED Post Cap Light for 4 x 4 Vinyl Posts w/ Wood Post Adapter (Black) LED LIGHTS - LED bulbs are the newest trend in lighting and can outlast the life of a compact fluorescent bulb by up to 10 times (even longer for incandescent). Traditional incandescent and CFL bulbs produce heat build-up that tends to overheat the area where they operate. LEDs prevent this excess heat output and result in reduced air conditioning costs. SOLAR POWER - These post lights utilize the natural power of the sun to operate. An amorphous solar panel absorbs light during the day and recharges the two 900mAh Ni-MH batteries for use in the dark. This eliminates your need to swap out batteries or install a costly outdoor power system. VERSATILE - Add light to almost any post no matter its size or material. With an included adapter each light can be designed to fit virtually wood, PVC, vinyl, or plastic posts between 4 inches and 5 inches in size. Simply snap on the included base adapter and screw it into your post and you're good to go. QUICK INSTALLATION - Stop making your life around the house harder and enjoy how quick and easily you can hook these lights up. Each individual lights include the adapter and parts required to get installed in an instant. Once installed you can relax and enjoy them every night without having to go and turn them on thanks to an auto on/off switch. BASE MEASUREMENTS - Base measures 5" x 5", wood post adapter measures 3.6" x 3.6", vinyl post adapter measures 4" x 4.