The adapter output V matches the rated input V of the device.( AC TO AC) OR (AC TO DC)

Example:

110VAC/6vAc or 110VAc / 6vDC

The adapter output can be greater or equal to the devices rated mAh or A. But not

less than current rating.

Example:

1200mAh is equal to 1.2A(amps)

Pick out the correct tip for your device and select the correct polarity.(Most Xmas units are center pin positive outer negative. Also if the unit needs  to plug in the bottom, you may need an L-shape tip.

Example:

see diagram below