These are the stainless steel rails that the heat shield slides side to side on for the Green Mountain Grill Jim Bowie Prime & Prime Plus pellet grill.
There are two rails per grill – placed in the front and the back inside the barrel. The heat shield is then placed on top of the rails. Then insert the Heat Shield Pull Rod through the hole on the side of the barrel into the inside and then twisting the rod into the side of the heat shield that has the threaded female port. This will now allow you to slide the heat shield side to side for optimal heat distribution without having to open up the grill to moving grates and drip pan out of the way to shift the heat shield directly.