Fisheye attachment lens
The Fisheye attachment lens is simply screwed onto the 58mm filter thread of the respective lens. The strongly curved lens simulates a fisheye optic with a considerably larger image angle. As with most of the attachment lenses, there is a small loss of light here as well. In addition, depending on the aperture value and intended use, slight edge blur is to be expected.
The macro fisheye adapter is not a complete replacement for a high quality fisheye lens. But it offers a welcome alternative to the often expensive and heavy lenses.

definition factor 0.38
0.38 stands for the factor by which the focal length of your camera lens is shortened. For example, 20mm becomes 7.6mm lens (f/0.38).

Also for the close-up range: always with you
A practical additional benefit is provided by the macro lens included in the set. It usually remains on the attachment lens and ensures enormous magnification at close range. However, it can also be used without the attachment lens.