You should always use a carbon grip compound when assembling carbon fiber fittings to your bike, such as seatposts, stems, forks, etc. These products can be expensive and you end up with a lot left over, since they come in sizes intended for use in bulk in bike shops.
This product is a 3ml blister pack of Effetto Mariposa's Carbogrip product, in a size that's more realistic for the home mechanic. It helps avoid unwanted movement of clamped carbon components, and is also waterproof, to resist seizing over time. Simply apply and wait 5 minutes until it dries to an extremely grippy surface. Cross Bike Review says: "We liked that my carbon bars and posts no longer slip when using Carbogrip, this stuff really works."