I bought these a month ago before I returned home to install them. The product is excellent, however, the holes are too close to the body of the light and a normal spanner, socket or even a tube spanner wouldn't fit to fix them to the concrete. I'm trying to find a thin-walled tube spanner for the job. I suggest that the holes be moved a further 3-4mm from the body of the unit.
This is a good sturdy light, nice and heavy metal cover, sealed from weather. It needs to be anchored down to a level area to work well. the white lights can shine out from just the two ends over 10 feet away. There is NO switch to shut off the light. I will be buying a few more for the edge of the driveway. They look like the reflectors in the middle of the street.