Will fit BB30 systems and also BB30A systems.

Best in class for weight, stiffness, and overall performance. Patented process, 3D hollow-forged alloy crankarms. FSA high-performance chainrings offer flawless 10 and 11 speed shifting. At a total system weight of 530 grams, the SI Hollowgram is one of the lightest production crankset in the world. There is no known other brand that can claim the stiffness-to-weight ratio of Cannondale's Hollowgram. The crankarms are constructed from a 2000-series aluminum that has nearly double of the fatigue life of other aluminium alloy. Crankarms are connected to thin-walled, and hollow pieces thanks to the "two-piece"-technology. In combination with an oversized 30 mm aluminum bottom bracket axle it guarantees superior balance of strength, weight and stiffness. The crankarms are CNC-machined for optimum strength and light weight. 

There’s a formula Cannondale use to help their sponsored riders win races and take championship titles: System Integration. Cannondale shaves weight, improves stiffness, and use fewer moving parts than other competitors.