Polyurethane Window Keystones

A window keystone is a decorative accent placed at the central apex of window arches or moldings. Historically structural in masonry, today it serves as an elegant architectural feature. Used on exterior windows, it beautifully conceals molding joints to create a classic focal point. Compared to heavy stone or plaster, polyurethane keystones are lightweight, putting no extra load on the window frame and ensuring a safe, risk-free installation. Highly resistant to water, moisture, and frost, they will not crack, crumble, or peel over time. They are easy to install with adhesive and can be painted with exterior paint. Polure offers high-density polyurethane window keystones with flawless details, perfectly matching classical architectural designs.