From the manufacturer's official website:

Thanks to Ultra-Drive™ geometry which defines the forms and machining of the sprocket teeth and nickel-chrome finish, the Chorus™ sprocket set ensures fast precise shifting that remains constant over time.

Also available from this year, the 11-25 combination is ideal if combined with CT-type cranksets.

Ultra·Drive™ - nickel-chromed finish - light alloy carrier - supplied without lockring (except for 11-23 and 11-25)

Nominal weight: 220 g.

For more information, please visit this product's webpage.