UPPAbaby Mesa Max car seat Infant inlay designed to optimize fit, better airway management, and body positioning for infants between 4-11lbs Infinite adjust headrest for a more accurate + customized fit No-rethread harness that adjusts with headrest Increased size of UPF hideaway canopy for extra sun protection and privacy (43% larger than current MESA canopy) 4th anti-rebound handle position for increased safety in rebound & rear-impact collisions when installing without the base Europea.