Have you ever stood in the garden center debating whether your planting bed was in part sun or part shade? Could those terms be any more vague? Now you'll know for certain! Place the SunCalc in the ground on a sunny day and twelve hours later you will have an accurate LED reading of the light level in that area. Plants can be expensive, save yourself time and money by choosing wisely. Runs on a single watch battery that will last 4-5 years.