Amazon.com: Piezo Electric Crystal Earphone Sensitive High Impedance Ceramic Ear Piece 3.5mm for Transistor Radio/Crystal Radios DIY Electronics Projects 1/8 inch Audio Jack Connector Wire Piezoelectric Element : Electronics
Amazon.com: Luvay 12Pcs Piezo Pickup Transducer Prewired - 27mm Contact Microphone Trigger - Discs Elements for Acoustic Instrument: Guitar, Drum, CBG etc. with Leads : Musical Instruments