Little piece is the speed sensor.
And about one-sided pedals... Today was a first day of a hard testing in different conditions (mud, ground, gravel and even a road in stones; before, after ). Clip-in is a little bit more difficult and takes maybe 1 or 2 more second in comparison with eggbeaters - you need to find the right side. But I'm more satisfied with these one-sided - it seems they are more robust and does not have a huge float like eggbeaters.
And now the first battle scars: http://instagram.com/p/m-SZK6iLKv/#
Hope it will not affect anything