It is called a Sure Stop brake system
SURESTOP Brake System | Safer, Smarter, Simpler Braking
I also found two YouTube videos, 1st showing how it works and 2nd is how to replace the active pad
Edited to add a replacement parts kit
http://surestop.bike/replacement-parts/
Last edited by JoeTBM; 11-28-20 at 10:20 AM.
Reason: Added part purchase info