Attitude Indicator (AI)
The attitude indicate provide pitch and bank information to the pilot.
Standard vacuum-driven attitude indicators rely on a gyroscope mounted in the horizontal plane. When he aircraft is pitched or banked, the spinning gyroscope stays rigid in space.
Most attitude indicators are accurate to +/- 100° of bank, and 60-70° of pitch. Beyond this, the gyro will tumble.
Some modern AI's will never tumble.