What Is It?
Weatherstripping is a durable flexible gasket put in place to make an airtight seal between the exterior door and door frame of an exterior door system, the sash and frame of an operable patio door, the operable glazed component of an exterior door system, or skylights when they are closed. The degree to which an airtight seal is achieved is a function of the type of weatherstripping used and the type of operable system.

Compression sealsCompression seals are seals that can be squeezed tightly together between the moving sash and frame. Generally speaking, they are the most effective kind of seals and are most commonly used on casement windows that are pulled shut by means of two or more latches. Compression Seal
Sweep sealsThis type of seal is a flexible fin usually made of rubber or polypropylene which is fastened to either the movable sash or the stationary frame and sweeps against the other component to form a barrier. Sweep Seal
Brush sealsBrush type seals (Pile) are most commonly found on sliders to facilitate the sliding movement. It consists of a brush mounted on the movable sash and the frame. Brush Seal
Magnetic SealsMagnetic seals are used on metal surfaces and magnetically attach themselves to the surface of the operable part as it closes. They operate exactly as the ones found on a refrigerator door and usually form the most airtight seal. Magnetic Seal