Every Sonos Controller ships with an AC Adapter, but if you've lost yours or have more cradles than controllers, you will need an extra. The AC adapter ships with a power cord included.

AC Adapter Technical Specifications
Input - AC100V - 240V, 50-60Hz
Output - DC 6V 3.8A
Colour - Light Grey
Dimensions - 3.8 x 1.7 x 1.1 in. (96x44x28mm)
Cable Length - 5.9 ft (1.8M)
Weight - 6.17 oz (175g)