slow and sear

Would any of you fine fellows be willing to explain to me the Slow n Sear accessory? Especially if you can explain it to me like I'm 5? I'm a dope. :)

*UPATE, the grill rehab is complete. I''m having some issues with photo uploads. Currently working on the pics and hope to have them up soon. My day started at this thread over hear http://tvwbb.com/showthread.php?65541-Would-You-Pay-350-for-this-Grill/page3 Thought I would follow it up here...