Grooved opin labalaba àtọwọdá ni a grooved opin nkuta ju shutoff labalaba àtọwọdá pẹlu dayato sisan abuda.Awọn roba asiwaju ti wa ni in pẹlẹpẹlẹ awọn ductile iron disiki, ni ibere lati gba fun o pọju sisan o pọju.