The versatile Colinwell Allan Block allows easy design and construction of retaining walls to meet specific engineering and site requirements. Walls built using Allan Wall Block Retaining Wall systems are quickly constructed and offer the perfect blend of performance, texture, colour and lasting value. Constructing retaining walls using the Allan Block mortar-less system is straightforward and easy. Built-in drainage, interlock engineering. Cost-effective and versatile. Durable and virtually maintenance free. Mortar-less dry stacking system means walls can be constructed regardless of weather conditions.