From the manufacturer's official website:

The Hollowtech II crank and bottom bracket combines race-proven hollow forging technology with the integrated crankset & bottom bracket. Weight is reduced while rigidity & power transfer is radically increased.

In addition to Hollowtech II integrated design; the crank arms are hollow which provide amazing strength and rigidity at a light weight.

Finally, SG-X chainrings enable super smooth front shifting. Special tooth profiles, pick-up spikes and ramps help make the front derailleur shifts quiet, easy and trouble free for you the rider.

Features:

• Crankset with integrated Bottom Bracket.
• Crankset includes BB cup unit (SM-FC6600)
• Crank Arm Lengths: 165/170/172.5/175mm
• Gearing:53-39T/52-39T

Specifications:

• HYPERDRIVE Yes
• DUAL SIS Yes
• Chain compatibility Super Narrow HG for 10-speed
• Hollow Crank Arm HOLLOWTECHII
• Reinforced Spider Yes
• Number of Teeth 53-39T/ 52-39T
• Bolt Circle Diameter 130mm
• Crank Arm Length 165/170/ 172.5/175mm
• Crank Arm forged aluminum/ anodized
• Chainrings aluminum/ anodized
• Average Weight 839g 53-39T,70mm, integrated BB

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