This simple apparatus clearly demonstrates the principles of resonance without requiring a water column or other apparatus.
Using the included 512 Hz tuning fork as a sound source, the inner tube slides inside the outer one and the student finds the point of loudest sound.
The tubes adjust from 25 to 38 cm which will tune over a range of approx. 452 Hz to 585 Hz at room temperature. Also includes 50mm plug to close end.