I install quite a few sleeves. My predecesser started using them and most customers now want them, I use them myself. Benefits inclued the ability to feel the sleeve in the ball before gluing it in to be sure the size is exactly what you want, and the knowledge that on the next ball the fit will be exactly the same if you get the same amount of bevel. For my balls I use Magic Carpet in the back of the hole and at least one piece of white tape in front, so my thumb doesn't come in contact with much of the sleeve. I do also install urethane slugs, it's just a matter of what the customer wants. -- JohnP