SAPHUE Transducer Acoustic Guitar Pickup Piezo Contact Microphone for Kalimba Acoustic Classical Violin Ukulele Mandolin Banjo Cello

I have not tested this out extensively. But initially, I have been very impressed with it. I put it on my mandolin and it sounds great on the small amp that I have. So far I am very happy with the product.

Works as claimed. It’s a bit noisy, picking up noise from cable movement. But given the low price it’s not a dealbreaker.