VFD253 integrates mutiple functions into a whole. As an audio spectrum analyzer: adopts dedicated green VFD display screen with 25 x 15 high resolution, the accuracy of each frequency band. As a Bluetooth receiver and audio switcher: besides microphone pickup, also with Bluetooth 5.0 and 2 groups of 3.5mm AUX input, works perfectly with your phone/PC/game player/amplifier/speaker etc. As a high- clock: using RX8025T built-in crystal oscillator whose clock accuracy is ±3ppm, year error within 1 minutes, very cool and interesting. Wide frequency range & special AGC display: 80Hz-16KHz frequency sweep, high- display even can do frequency point test. Speical AGC algorithm and customized output curve, ideal visual effects even the input signal is in a small to large range, avoid that no display when input low and display in full screen when input high. Many adjustable items & display effects: gain, brighntness, falling speed of main light column, holding time and falling speed of the can be adjusted separately. 5 music spectrum display mode and 2 clock display mode, all settings with power-off memory function, no need to set again after restarting.