From the manufacturer's official website:

The Pro Light™ lightweight road racing tire takes Michelin’s most advanced technology and brings it to you at a weight of under 200 grams.

THE CASING: The Pro Light™ tire uses the same casing as the Pro Race™ road racing tire, but doesn’t include the high density puncture protection ply under the tread. While this may affect durability, it does improve rolling efficiency and lowers the weight.

THE TREAD: The same Silicium™-based tread compounds used on the Pro Race™ tire are utilized for the Pro Light™ tire, resulting in enhanced cut resistance, improved grip and super low rolling resistance.

THE PROOF: Under world class teams like AG2R Prévoyance, Alessio, Brioches la Boulangére, FDJeux.com, Jean Delatour, Landboukrediet-Colnago, Milaneza-MSS, Rona-Esker, and Saturn, the Pro Light has proven itself ideal for time trials and other events where every gram counts.