1. Due to the magnetic field, multiple compasses cannot be approached when in use, which will affect the accuracy.
2. When using, it should be placed still, and at the same time, use the level to determine the level, and then read it, so as to accurately determine the direction.
3. The earth has a magnetic field, and the pointer shown will deviate, but the compass on the mobile phone is not affected by the earth's magnetic field. so it is not accurate.