Before you choose a plant for a spot in your yard, use the SunStick to accurately measure sunlight and shade over the course of a day. The SunStick determines if a location is sunny, part-sunny, partshady or shady. You can then select a plant that matches the available light for perfect planting every time. Kit includes 3 single-use sun disks, 3 stems and sunlight color chart. Refills available.