We offer a full selection of keystones designed for use with crossheads. The decorative keystone adds detail to the crosshead and quickly enhances trim overall. Whether the desired effect is subtle or dramatic, the decorative keystone brings you the versatility that you seek. The flat keystone is precision molded in urethane. The back of the keystone interlocks with the moulding profile of the 9" and 10" crosshead with bottom trim. The flat keystone is non-porous, so it will not be vulnerable to the warping, staining, mildew and decay that moisture can cause in wood trim. The urethane keystone is pre-primed and ready for finishing and attachment.