The Low Voltage LED Dome Side Light by LMT Mercer is a small fixture that makes a big impact on posts or rails. It is dimmable dding LED lighting to your outdoor space is a snap with this Solar Dome Light from LMT Mercer. It doesn't require a transformer - it is powered by the Solar Collecting Post Cap (sold separately) and wiring is concealed within your post sleeve. The light is 2-3/4 in diameter and comes in five colors to complement vinyl, composite or wood posts.