This convenient 1.3mm DC to 2.1mm DC adapter cable lets you plug one of our into !

2.1mm inner diameter (5.5mm outer diameter) is the most common type of DC plug, but you can use this adapter for anything else that has a 1.3mm ID (3.5mm OD) DC jack!

Please note you have to exert a little more force than expected to plug it into the adapter.