It is made by depositing aluminum on a hemispherical plastic. The inside is a concave mirror and the outside is a convex mirror, so you can clearly see the difference in the image due to the irregularity.
Another feature of this instrument is that you can see a real image of your finger sticking out from a concave mirror.
Specifications
Mirror diameter: 150 mm
Details of the experiment
experiments to see the real picture
You can experiment with sunlight.
*Sunlight focuses in a concave mirror, so don't leave it in the sun.