First off, the plastic tube that comes with this product is useless. It isn't big enough around to fit inside leaving the sleeve loose around it. Also, the ends of the tube are pretty sharp, so using it would eventually over time ruin the sleeve it is made for. To use the sleeve without the tube as an extension, the guy would have to be 9"-10" and super thick already, which makes it unpractical for the average male. We got the Doc Johnson 10" extension (which is made for guys who are 5"-6" long), and rolled this one over the top, and the sleeve fit perfectly over the top of it. What we were left with was a snug fitting extension that measured almost 12" long. While the wife can only take about 9 or 10" of this toy, it is still one of her favorites as she loves the extra girth, and the ability to go extra deep in the heat of the moment. The shape and texture is great, so if you have another extension or toy that you would like to add a couple of inches to, and some extra girth, for the price this product I would highly recommend.