That's a total waste of money. If you're worried about rust, use jb weld to stick a tab with a hole in it to the lid of the corny. Then, use a mesh bag.
Or, ferment in primary for a month (this in itself has MANY benefits). After the first 2 weeks, add hops. I've had awesome results....you're basically doing primary and secondary in the same vessel. For double-dry-hop awesomeness, also add a non-rusting herb ball of hops to the keg.