I know this has been asked a thousand times before, so I apologize but I couldn't find the threads. My 74 year old dad has finally decided to try vaping because Mom's cardiologist thought she was still smoking. I'm going to give him my old ego gear and the associated paraphernalia, but I don't know what topper to get. I've decided on carto rather than clearo tanks for consistency, but don't know which one. I need something he isn't gonna have to screw with much and has a nice big hole for filling. Recommendations anyone?