The Intellitouch PT10XL Traditional tuner pushes the boundaries for small, compact tuners while boasting a large, easy-to-read, backlit display. The Intellitouch instrument tuner uses the latest in digital technology. A state-of-the-art, low-power digital signal processor analyses the pitch of your instrument and displays it on the PT10XL tuner"s large, digital crystal display for easy reading. The PT10XL tuner"s display offers the original arrow-type display standardized by Intellitouch. Its innovative backlight shows red when your instrument is out of tune but switches quickly to green as soon as your instrument goes into tune. The Intellitouch PT10XL let you use microphone input and a 1/4-inch guitar plug input. The Intellitouch tuner can be recalibrated between 430Hz and 450Hz using the A-Ref button. Intellitouch tuners come with a no-questions-asked manufacturer"s lifetime warranty.Extremely accurate Seven-octave response Arrow-styled display Color-changing backlight: red = out of tune; green = in tune Calibration from 430Hz to 450Hz Elegantly simple controls Microphone and 1/4" guitar inputs Manufacturer"s limited lifetime warranty Tuning range: 7 octaves: 27Hz - 6,000 Hz Tuning precision: Better than one cent Battery life: 30 hours of continuous use Power supply: 3 volts Battery type: AA size; two batteries required (not included) Dimensions: 2.55" H x 4" W x 3/4" D Weight: 2-1/2 oz.