Specifications: This board support bluetooth-compatible audio reception, convenient to use. The power amplifier has advantages of pre-amplifier and low frequency processing. It is features with bass, left and right channel volume adjustment, treble adjustment, master volume potentiometer. Item Name: Power Amplifier Board Material: PCB Core Chip: TPA3116D2 Power Supply: DC 12-24V Operating Voltage Range: DC 11-25V (Current 3-4A, or 19-24V/4-5A, if the Power Requirements are High, 20- 24V /8-9A or More) Bluetooth Receiving Distance: >8m (26Ft) Speaker Impedance: Left/Right Channel: 4-8Ω, Bass Channel: 2-8Ω Maximum Output Power: 50W(L), 50W(R), 100W(BASS) Attribute:1#: With bluetooth-compatible Power Amplifier Board; 2#: Without bluetooth-compatible Power Amplifier Board Features: High Efficiency, High Power, Portable Size: 10cm x 10cm x 2.5cm/3.94" x 3.94" x 0.98" (Approx.) Notes: Due to the light and screen setting difference, the items color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 1# 1 x Power Amplifier Board (With Bluetooth) 4 x Stud 1 x Nut 4 x Gasket 4 x Screw 1 x Power Cord 5 x Key Cap (Random Color) 2# 1 x Power Amplifier Board (Without Bluetooth) 4 x Stud 1 x Nut 4 x Gasket 4 x Screw 1 x Power Cord 5 x Key Cap (Random Color)