Loosening the screw that secures the battery cover exposes the retinue of 6 - count 'em - 6 x D-cell batteries that supply 9V to the radio. You are looking at the outer row of three batteries; there's another row behind that. There is also space to the right of the batteries for storing the included external antenna and earphone.

There are two earphone jacks as well as an external antenna jack on the upper right section of the back.