Lithium-ion battery
The iPhone featured a Samsung 32-bit ARM microprocessor, underclocked from its stock 620 MHz to a slower 412 MHz to increase battery life. The iPhone also included several sets of sensors, including an accelerometer, a proximity sensor, and an ambient light sensor. Similar to the iPod Touch, the iPhone also featured a 3.5 millimetre auxiliary headphone jack. The phone also had a 3.7 V 1400 mAh Lithium-ion battery built in it.