All rollers are self-skinned, soft feel polyurethane. They are designed to last a lifetime of felting under normal use. (They will stain if exposed to dye).
Your Gentle Roller comes complete with an all-purpose drive roller.
If you are a prolific felter, or looking for maximum efficiency when felting, you can add a second drive roller to increase your felting efficiency by up to 100%. Read here: The Benefits of Using a Second Drive Roller.
There are two options for an second or accessory drive roller: While an all-purpose drive roller can do just about anything, a super-soft drive roller is specifically designed for very fine nuno items and heavily textured items. Read here: The Benefits of a Super-soft Drive Roller.