This is the new Velocity A23 rim shape. It is now tubeless ready, but you can still use standard tube/tires. The new shape gives a more secure hold to a tubeless tire, makes is easier to mount, and helps prevent burping. Burping is a sudden pressure drop when the bead loses temporary contact with the rim bead. My rims come with Veloplugs (still fits this rim) installed unless you want tubeless tape.