7.5V wall adapter, not commonly available. The best part of this adapter is that it allows an Arduino project to run independently. For projects that need a motor or servo, 5V may not provide sufficient power, whilst 12V can prove too much and may cause overheating. 7.5V is just the right voltage for those projects, safely providing the needed power. Comes with a DC2.1 connector which is compatible with the Arduino power jack. Plug&Play!