AC/DC adapter

I purchased my Proteus some time last yr and have not had much use of it myself since a friend seemed to have greater need for it at the time. I've been reviewing the manual and contents that were shipped. Amongst the cables is a 7.5V AC/DC adapter and I've noticed a small connection port on the side of the Proteus that reads DC 7.5V. There is no mention of the adapter in the manual that I can find in the section concerning what ships with the Proteus and I can only find reference to battery usage in the manual. Common sense tells me that it is an adapter that I can use instead of batteries but before plugging the adapter into the Proteus I want to make EXTRA sure that this is indeed what it is for and that the cable was not added into the collection when I retrieved it from the person that was previously using it. Seems like a common sense assumption but I don't want to fry the unit by doing something stupid and plugging it into the wall.