Ideal for solid-grouted, non-exposed or covered structural walls, Grout Lock is a stretcher unit designed for high-production installation. Head joints are eliminated, open end faces are tapered to allow for grout keys, and the face ends have interlocking flanges conforming to ASTM C90 Note 8. Face ends have a bevel to simulate a head joint; however, it is recommended that Grout Lock units remain exposed only in areas with utilitarian, non-aesthetic uses.