A quick visual inspection at the Shimano SLX crankset indicates a two-by version on the left using a different spider design than the triple crankset pictured to the right. And the use of Torx chainring bolts indicates that they may be made of aluminum.

Shimano SLX M670 10 speed Crankset
The bold shape of the SLX crankarms is a welcome sight for strength, for getting used on everyday mountain bikes. And even better yet are the  gearing options. It has new school options of 24,32,42 as a triple crankset, and three choices for the SLX double chainring- 40 x 28, 38 x 26 and the new, 38 x 24 gearing that’s going to pair better with 29er bikes. The chainrings have stamped and pinned ramps with the fast shift action that comes from most Shimano cranksets. Similar to XT, the SLX crank arms are built separate from the aluminum four arm spider.

29er Mountain Bike Technology
Shimano has missed the boat on 29er bikes  two times now. The first when they unveiled the recent XTR and a two years ago with the new XT groups. The SLX incorporates a low-profile front derailleur making room for 29er mountain bike tires, a smaller 38 x 24-tooth gearing choice for the two-by crankset, and a direct mount rear derailleur that will adapt well to 12-millimeter through-axles that most designers for 29er bikes are using in the rear of these frames to increase stiffness. The Direct Mount will eliminate the Shadow derailleur’s B2 link and the replaceable derailleur hanger with one peice, and can be used with both the standard quick-release or a through-axle.
Shift Lever Goodness
They are reporting the new Shimano SLX M670 shift levers have seen big upgrades having the crisper, more positive action of the XTR and XT brothers. The triggers have been redesigned to make ergonomics better and the front shifter can be changed to be used for two or three chainring cranks using a XTR style switch. SLX shift levers come with handlebar clamp or multi mount version.