A 440 Hz Tuning Fork - Steel Guitar Shopper and Forum Store
Amazon.com: A Tuning Fork - "A" 440 Hz with Soft Shell Case : Musical Instruments
Tuning Fork 440hz Standard Sound for musical Instruments Germany A Tone Fork | eBay
KaWe tuning fork with plastic base, a1, 440 Hz
A tuning fork of frequency 440Hz resonates with a tube closed at one end of length 1.8 cm and diameter 5 cm in fundamental mode.The velocity of sound in air is?