This one works very well, the smaller sleeve was too tight and the longer ribbed one was larger and worked better for me but I'm not small to begin with so they are trying to cover all the bases I think. The ribbed one is also longer than I preferred but it is easily cut to whatever size you want and once you dial it in, it only takes about 10 pumps and your dong is fully hard and swelled up and ready to go! If you have a **** ring put it on before pumping up your ****, it will stay harder longer that way but be careful not to pump it up too much if you do it that way, the release valve works but extracting your hard **** can still be a little difficult.