I'm close to five inches in girth, and my friend is about 5.5. I went in first and he slowly pushed his in as well. Lots of lube. We sat facing one another, our balls touching. He controlled the fleshlight and he moved it up and down and twisted it a bit. Then he held it in place and started fucking it, and I could feel his dick slide up and down mine. It was pretty intense.
The sensation is completely different than when you use the fleshlight by yourself. I know that sounds obvious, but the other dick inside of it takes away from the sensation of the sleeve itself. However it makes up for it by being incredibly fucking hot.