This unit is used for field matching and field "fitment" as needed for on-site retro-fitting for numerous older wood casement windows from the 1970's, 1980's, 1990's and beyond 2000's - this unit ships in a 27" Overall Length. Casement Sill Stop Wood Cover Housing replacement part for many old wood casement windows. They come to you as an unfinished a-grade wood component, and we suggest you seal all sides.