Unlike the standard cat's eyes you will not only seen here from the side, but also (almost, of course, covers the Tire reflectors when viewed from the front) from all other directions.
Particularly important in Germany: the road vehicle! Some of the tubes have printed a test number, according to instructions should be (if it even comes to a control) install at least one of these tubes with said number.
In addition, these are to be used as a total replacement for cat's eyes, they must not be used in addition to other (spoke) reflectors.
All in all worth every penny, the margin of safety is immense.