This is a 2.8” Closed Cell Foam Insert. Pro-Line has developed a new closed cell insert for all the Trencher 2.8”, Masher 2.8” and Sand Paw 2.8” tire Fans!! Closed Cell inserts have been used in racing for years because they are extremely durable, waterproof and shaped to exactly fit the tire. Now, this technology has made it to the realm of the extreme bashers who need inserts with extreme durability! Closed Cell foam inserts are stiffer than standard foam, so they perform much better under high loads and help to reduce tire ballooning at high speeds. If you are serious about bashing, then Pro-Line’s new 2.8” Closed Cell Foam Insert is for you!