Nobsound 2PC Audio Power Amplifier Panel VU Meter DB Level LED Header + 1PC Driver Board Module DIY Taiwan production, high quality, cute appearance, stable and reliable performance, Display high precision and with backlight. dB: -20~+5dB; 0dB=1.288V+/-10%, calibalated; DCR= 650, If=450uA; Lamp: White LED x1pcs ,10~20mA (Original design has no resistor inside, so need extra one to work); Led Lamp voltage : 2.2~2.6V So, you need the extra resistor : 270 1/4W ,if VDC=5V 390 1/4W ,if VAC/DC=6.3V 1000 1/2W ,if VAC/DC=12.6V Also need external resistor, diode, capacitor (if 1Khz 0dB=1.288Vrms, R1=470,VR1=100, or R1+VR1=500) Dimension: 35.0x35.0x38.0mm, WxHxD; View size: 34.0mm; Mounting hole/pitch: 3.5mm/28.0x28.0mm; Note: On the center 2 pins are for meter coil, other 2 pins are for LED