Accentuate entryways, doors and windows with the addition of a decorative keystone. The flat decorative keystone installs easily for beautiful results, whether you envision something subtle or grand. The flat keystone offers cost-effective, versatile and durable solutions. We offer a great selection of keystones designed for use with specific mouldings and crossheads. This flat keystone compliments moulding MLD220. The back of the keystone interlocks with the moulding profile for a perfect fit. The flat keystone is molded with precision to provide you with excellent results in installation, appearance and durability. High-density polyurethane foam is strong, but also lightweight and easy to work with.