BeSafe iZi Modular A X1 i-Size: This seat with the ‘A’ in its name is almost identical to iZi Modular X1 i-Size, but in addition features the Active Retract Harness™. The revolutionary belt system is the only harness that helps parents with buckling their child up. It features an advanced retractor construction on the inside that continuously pulls in the belts. That way, parents simply push up the belts inside the shoulder pads for a tight fit, and done!