Complex sentence: The new roof, a cable-supported retractable roof system first used with the Commerzbank-Arena in Frankfurt, Germany, is the largest of this kind of cable-retractable roof stadiums.
Split into simpler sentences: The new roof is a cable-supported retractable roof system, first used with the Commerzbank-Arena in Frankfurt, Germany. It is the largest of this kind of cable-retractable roof stadiums.