28BYJ-48 Steeper Motor 5V
This unipolar motor is perfect for people who are new to Arduino.
It has a built-in mounting plate with two mounting holes. There are only 32 steps (11.25 degrees) per revolution, and inside there is a set of 1/16 gear reducers.
The shaft is flattened, making it easy to attach objects to it using a set screw.