SOSS 218IC Invisible Spring Closer HingeThe SOSS 218IC is a 7″ heavy-duty invisible spring closer hinge for doors with a minimum material thickness of 1-3/4″. Constructed of zinc and steel with nylon links, it remains completely invisible from either side when the door is closed. UL labeled for use on hollow metal, sheet metal, tin clad, steel composite, and wood core swinging fire doors and frames with a 20-minute fire rating.Key FeaturesInvisible When Closed: Fully concealed from both sides; can be installed inside the door or inside the door jamb.180-Degree Single-Action Operation: Opens a full 180 degrees as a single-action hinge.Adjustable Closure Rate: Closure speed is adjustable with an allen wrench after installation without removing the closer.Heavy-Duty Construction: Zinc and steel body with nylon links for added strength in demanding commercial use.Hardware Included: Wood and machine screws included.Certifications and ComplianceUnderwriters Laboratories (UL) Labeled20-Minute Fire Rating on qualifying door and frame assembliesTechnical SpecificationsSize: 7″Min. Material Thickness: 1-3/4″Material: Zinc and Steel with Nylon LinksCorner Type: RadiusDuty Level: Heavy DutyApplication: Full Sized Entry, Metal, WoodFire Rating: 20 MinuteCompatible Door Types: Hollow metal, sheet metal, tin clad, steel composite, wood core swinging fire doors and framesElectronic: NoPower Transfer: NoCounter Bored Screw Holes: NoScrews Included: Wood and MachineCommercial/Residential: CommercialSold As: EachTypical ApplicationsCommercial Office BuildingsEducational FacilitiesHealthcare InstitutionsRetail EstablishmentsIndustrial and Warehouse FacilitiesMulti-Tenant Residential PropertiesGovernment and Municipal Buildings