286809 Features: red and green dual color backlight negative， classic appearance， accurate and sensitive tuning， stable pointer Tuning items: guitar， bass， violin， twelve-tone equal temperament Color: black Size: about 53 x 80 x 43 mm Signal receiving method: MIC/CLIP A4 frequency range: 435 Hz-445Hz Debug : C， F， flat B， flat E Power supply mode: 1 x Button battery CR2032 ( not provided ) 1 x Tuner 1 x English user manual In original package