For bass piezo bridges, there's the Schaller Bass 2000 series. Also Graphtec Ghost bass piezo saddles for P-style, ABM or Hipshot A style bridges (you can get the A-style complete with the piezo saddles from Hipshot). Those seem to be the main ones.
Oo a Schaller would be nice...😀
"Music is in the air; it's my job to pull it out."- Jaco Pastorius