20pcs 27mm Diameter Piezo Discs Piezoelectric Ceramic Copper Buzzer Film Gasket by Uptell: Amazon.com: Industrial & Scientific
Amazon.com: Parts Express SPST NO Momentary 22mm Stainless Steel Waterproof Touch Piezo Tamper Proof Switch with Red Ring 3-24 VDC : Industrial & Scientific
Amazon.com: Ultrathin Red Pickup Under-Saddle Passive Piezo Film Pickup Sticks for Acoustic Guitar with Plug : Musical Instruments
Amazon.com: Goedrum Pack of 5 Prewired 35mm Piezo Disc and Double Sided Adhesive Foam Circle : Musical Instruments
Piezo Ceramic Ring Φ38mm – Sino Sonics
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
Amazon.com: 3-pack 27mm Piezoelectric Disk Elements (Contact Pickups) with 2" Leads : Musical Instruments