Keeping the backyard pool at just the right temperature takes the right pool tools, Swimline has everything you need from gear to clean and maintain the water quality and keep it at a comfortable temperature. The Swimline Hydro Tools Jumbo Easy Read Thermometer is an extra-large 10 (25.4 cm) for easy reading and retrieval from the pool. The wide blue plastic backing with eyelet for fastening the cord has brightly colored in yellow temperature gradient in Fahrenheit and Celsius for easy temperature readings.