York AirSill™ aluminum flashing receivers provide an alternative to traditional installation methods for flashing attachment at wall openings. Typically flashing is secured with mechanical fasteners such as nails or screws to the return surfaces of the rough opening framing. Fenestration assemblies (e.g., windows, doors, storefront, window wall, curtain wall glazing, louvers, etc.) typically conceal the return surfaces of the rough opening framing once installed, prohibiting access to the mechanical fasteners and the flashing mounting surface. The flashing is installed before installing the fenestration assembly, which has an impact on construction sequencing, trade coordination, and schedule. Note that replacing flashing would require the fenestration assembly to be removed. Many times the flashing at wall openings is included in the cladding subcontractor scope of services, which tends to force the cladding to be installed before fenestration assemblies, delaying “dry-in” of the building enclosure and interior finish work. Further, the typical traditional method of flashing interrupts critical fenestration seals with the building’s air barrier, allowing a potential path for air leakage and water penetration into the building.