Audioline PowerTel M4000. Display diagonal: 44.4 mm (1.75 "), Display resolution: 128 x 160 pixels. Data network: GSM, GSM bands supported: 900, 1800 MHz. USB connector type: mini USB A, Headphone connectivity: 2.5 mm. Ringer type: monophonic. Battery technology: Lithium-Ion (Li-Ion), Battery capacity: 750 mAh, Talk time (GSM): 2.5 h