A Sill Horn is the extension of the sill to the exterior of the brickmould or casing. This is a decorative choice and is common in colonial and authentic classic trim packages.
Sills with a metal saddle will use a sill extender to create the sill horn.
Wood sills will use a longer sill and create the horn by cutting the sill. It is important to specify the length of the horn when ordering the unit.
While the horn can be cut to match the outside of the casing, if no casing is selected specifying the horn length is mandatory.