From the manufacturer's official website:

Carbon fibre immediately indicates a component's competitive spirit. So just imagine if the component in question is the very soul of the racing bike: the rear derailleur. The carbon front link says it clearly: the Chorus™ groupset is designed for racing.

Available with a short or medium cage, to interface perfectly with double and compact cranksets. Short cage derailleur for combining a double/compact crankset with a 13-26 sprocket set or smaller. Medium cage derailleur for combining a double/compact crankset with a 13-29 sprocket set or smaller or triple crankset with a 13-26 sprocket set or smaller.

Short cage: Upper to lower pulley-axle: 55 mm.
Nominal weight: 202 g.

Medium cage: Upper to lower pulley-axle: 72,5 mm.
Nominal weight: 205 g.

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