The Sak II is a reversible and removable airbag designed for the Kruyer I I and for the Karver II . The Kruyer II/Karver II-SaK set allows total flexibility. If in addition you add a ventral reserve, all types of flights become possible. It is fixed in 2 minutes by six points on these harnesses: two legs under the thighs, one in the lower back and two at the level of the back and one at the top of the back. The addition of the SaK II improves the comfort and precision of the harnesses. The side triangle adds adjustable lumbar support and more direct action on the wing when piloting in the harness.