Product review (1 stars): Received a defective unit -- isn't level.
Ordered to replace an identical (original, appx 2 yrs old) cartridge that I broke when I dropped the edge of a pot on it. Cartridge received from seller "Superior Supplies" appeared to be new and flawless, but wouldn't seat properly in the bay. It's clearly warped or otherwise not level -- when cartridge is installed and three corners of its glass-surface edges are in contact with the range body, the fourth corner has about an 1/8th inch gap between its lower surface and the top of the range. Press down on that corner, and the diagonally opposite corner pops up 1/8 inch. Considering how (relatively) fragile these glass tops are...no way.

I imagine having full heavy pots on both elements could easily result in the whole thing cracking in half. And the original cartridge didn't have this issue -- it fit perfectly and completely level. Not sure if this is bad stock or if I just got unlucky, but I don't know how this unit made it through quality control. Grateful for Amazon/Superior's return policy, but leery of ordering another one. Returning, and probably purchasing (for more $) through my local supplier instead.