In VERSA-LOK's unique system, pins are inserted in the holes of an upper unit and tapped into receiving slots of two lower units. Top-pinning makes installation easy because the units do not have to be lowered onto pins. Instead, pins are placed in units after the units are set near their final position. VERSA-LOK’s unique hole-to-slot pinning allows variable bond, which is a structurally preferable installation method. Variable bond eliminates the gaps between units that are necessary with wall systems that require exact half-bond installation. The hole-to-slot pinning system allows units to be adjusted horizontally as needed during construction, and it allows vertical joints to wander in relation to joints in courses above and below.