The official RPi Cameras already come with lenses so you don't get a choice of optics. This kit solves that problem and includes not just a useful selection of lenses but also with 4 lens holders to enable the lens changing process, allowing you to experiment with a range of focal lengths with a horizontal field of view ranging from 10 to 200 degrees.
In the box:
Watch the video to see how you change the lens holder and lens.