A reglet is an interlocking two-part flashing between a wall (or the back side of a parapet) and a roof. Reglets usually consist of a receiver flashing affixed to the wall with fasteners and a bead of sealant, and a counter flashing extending from the wall over the roofing material (usually a membrane roof). The counter flashing is removable to allow for the roofing material to be removed for re-roofing.
Some reglets are one piece. Sometimes with two part reglets, the receiver flashing is embedded into masonry walls for long lasting weatherproofing. The term reglet is also sometimes used to describe a long, straight decorative moulding. The term reglet is derived from the old French word for ruler, because it is long and straight.