CLEAN? Durable fusible link operating element Gasketed cover plates limit air and dust movement through the ceiling New Model G4-11, K11.2 Flat Plate Concealed Sprinkler OR DIRTY? For today's Extra Hazard Occupancies The industry's ONLY lineup of rugged standard response fusible element K11, K14 and K17 spray sprinklers. And introducing the new G4-11 concealed sprinkler with a gasketed flat plate for industrial clean room applications or other finished areas.