From manufacturer's official website:

The teeth of the Record™ sprocket set have an Ultra Drive™ design that integrates the chain and chainwheels of the crankset to ensure fast, precise and consistent shifting through the years.

The 11-25 combination is available from this year and is ideal if used with compact cranksets.

Ultra·Drive™ - nickel-chromed finish for steel sprockets - light alloy carrier - supplied without lockring (except for 11-21, 11-23 and 11-25)

Nominal weight: 188 g.

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