Originally shared on the public FactorioPrints / Factorio School archive (factorioprints.com · factorio.school). Authorship preserved from the public catalog.
Parameterized throughput-unlimited 5 to 4 belt lane balanced quality filter. Items above normal quality are output on the top belt. Will always output 4 fully lane balanced belts of an item at normal quality as long the amount of input items above normal quality is <20% (1 input belt's worth) when fully saturated.
