The Flatless Tyre system is a foam tube that is to be inserted into a mountain bike tyre, and it significantly reduces flats. It consists of both air and foam, and has a tube already included. It acts as a spacer between the tube and the tyre, effectively stopping sharp objects from puncturing the rim, and reduces rim strikes and pinch flats (snakebites), preventing damage to the rim. The Flatless Tyre comes with an inner tube which needs to be filled with air after installation.
This is the 27.5" size.