FIVB approved volleyball features Flight Stability Technology. Has premium micro-fiber cover. Official size & weight. For indoor use. 2-year warranty. MINIMUM OF 3 BALLS MUST BE ORDERED. Flight Stability Technology (FLISTATEC) achieves a stabilized flight path by controlling the air disturbance around the ball through the placement of raised hexagon-shaped designs on the surface of the ball. Irregular flight patterns are significantly reduced with FLISTATEC.