The seal coming with the mytivac
cylinder is very useful in pumping, it will stop the part of the scrotum going in to the
cylinder. When I got it, I got doubt how the 5'' penis can go inside as the hole of the slicone cusion is very small. But I found the idea to get in easly. Put some KY jelley on the hole of the silicon seal cushion and little on the glans ---- then press the tip of the glans against the hole and slowly pump. You can see the penis will slide easly and get in to the
cylinder. Hope it helps