Green is the memory cell for the iron plate inserter.
Grey resets the count every 100, just so it remains easy to read.
Red handles making sure that the iron plate inserter only inserts in batches of 5, so no iron gets stuck in the furnace. Is there are better way to do modulo? I'm doing [input/5] as red, [input+4/5] as blue, inserter stays on if blue > red.
I'm using side inserters, which is why the right most filter inserter (that pulls any spare iron out of the output) is oriented the way it is (it dumps into the wooden chest, which the fast inserter on the right puts back on the belt). The other filter inserter removes the steel to the provider chest.
blueprint