Wide pedal platform for foot-pedal stability.

Low maintenance sealed cartridge axle unit. 

Large binding target for quick engagement.

Adjustable cleat tension with indicators. 

SPD-SL: These pedals work with SM-SH10, SM-SH11, and SM-SH12 cleats.

Includes SM-SH11 cleats

These are the Light Action version of the R540 pedals.  This means that the cleat retention spring requires less effort to un-clip.  The decreased retention force is good for a number of applications.  These pedals are easier to clip in and out of, which makes them great if you are new to clipless pedals or worried about clipping in and out.  These are great for helping you to not fall over in case you suddenly need to un-clip.  

The downside of the light action pedals is that they are more likely to disengage when you pedal very hard, like a sprint.  As a result, these pedals will work best on a commuter or a fun/fitness bike.