It says nothing/shows nothing about a plug-in, but says nothing about batteries, either. It does say the lens is 3 1/2" diameter and magnifies 1.75, the small inset lens is 3/4" diameter and magnifies 4X. I think the lens cover might be pretty handy... :) You might want to call them Tuesday morning, cause I don't do this for a living--I was just reading the box. :)