My understanding is a lot of new pipes have that; I looked at a Sav at the B&M last week that had one. The Grabow I started with had one and it started to build a cake within a week. As it was explained to me, it's to help protect the blow and speed break in/cake buildup. I've read that some think the cake that forms on it isn't very strong though so I imagine that as with most things pipe related YMMV.