That's exactly what they are, they give the exhaust a place to vent so that they don't choke down the flame. Others have used more intricate methods, such as venting gas to the rear of the stand. There are some photos of this on brewers hardware website somewhere. drkwoods did a stand that mine borrows a lot from and he engineered a two piece windscreen with a chimney/stack type deal to vent exhaust. I don't have the link handy but if you do a search for his user name it should come up. I decided to go with these standoffs because they are simple and I already had the half inch bar stock.