45mm 

Operation: To be normal music source 0.5watt

Input: To be normal oscillartor 5.0 volt

Impedance: 8-25Ω±15% measure at 1KHZ

Resonant Freq.: 550hz±20% measure at 1 volt

Freq. response: 400-6000 hz

Sentivity: 87±3dB

Destortion: ≤5%