Here's a pickup I made for my double bass. It's the type that goes under the bridge. The second photo is an installation example. The sensor sits on a maple base, so I think it's gentler on the top plate than copper foil types. This is also true for the real thing (lol), but the body is thicker than copper foil types, and the bridge leans towards the 1st string side, so you'll need to use adjusters to compensate for the difference, otherwise it will affect the acoustic sound and playing feel. The sound is clearer than copper foil types, but on the other hand, the gain and the feeling of the sound being pushed forward are weaker. However, some people may prefer this type depending on how they use it. You'll need to secure it to the tailpiece or similar using either cable ties or an arc-shaped clip. It's new, only tested for functionality, and has a handmade feel.