Drum trigger. This is used to send a signal from a drum head to a control module. I have tested this with the Roland TD-17.

I used the Piezo from Amazon
https://www.amazon.com/dp/B07B8RJ8NX?psc=1&ref=ppx_yo2ov_dt_b_product_details

And the Jack also from Amazon
https://www.amazon.com/dp/B08FDR6HXK?psc=1&ref=ppx_yo2ov_dt_b_product_details

I also used 1/2- 3/4" think foam to make contact with the drum head. You will also need an M6 screw and nut. The M6 knob is from Dobhar