My turn to show off a(n emergency) brake disk – I’m told one stop wears it out

Normally we use regen braking through the traction motors, and this disk brake is just for emergencies. Its on the back of the traction motor, which is geared up about 100:1 from the wheel. I’ve never actually seen the ebrake get used, so I’m not sure exactly how long it lasts, but definitely not long. Its 1″ thick for scale