The premium base with Load Leg and built-in Anti-Rebound Bar act together to reduce rotation caused by an accident by 50%. The load leg can be adjusted up to 10 different positions and is able to be folded under the base when not in use. An Energy Management Foot at the bottom of the Load Leg activated during a crash by crumpling and absorbing energy away from the baby.The base is compatible with all Peg Perego Primo Viaggio 4-35 infant seats. (Primo Viaggio 4-35, Primo Viaggio 4-35 Nido & Primo Viaggio 4-35 Lounge)