Sheer Plate for Mahlkoenig EK43 - V2. Previously made from aluminum, Mahlkonig's Sheer Plate is now stainless steel, and thus much more durable when it comes to frequent start/stop action. 
 
These little plates are designed to break under load inorder to protect the grinder motor. Once designed to break if a rock jammed the burrs, they now commonly break due to the start/stop action of EK43's being used for espresso rather than retail coffee.