Hookless tyre is the new trend on mountain bike. The theory of hookless tyre is same as the tubeless in road bike. By creating a seal in conjunction with a special valve stem and a viscous liquid sealant within the tyre to get tubeless. It has been the first option in mountain bike.
The advantage of hookless is that by creating rims without bead hooks, we can improve the stiffness of the whole rim and get the impact resistance of the rim to improve by a lot. At the same time the precise tolerance between the rim and tire bead, plus its specific square shape, help the tire bead lock securely into place on the rim. Furthermore, the tire bead is controlled for how much it can stretch when inflated, which is very little to not at all. These characteristics create a very safe and secure bead lock. The tire tends to stay in place even when deflated. And, the tire can be run at different pressures with no fear of the tire exploding or rolling off the rim. Of course the valve is a critical component of the hookless as well - it must be properly mounted in the rim to maintain an airtight seal.