A 6″ x 16″ double-sided segmental retaining wall, with tapered sides and an independent mechanical interlock, allowing for a vertical or battered wall. Semma also has tremendous shear strength (block to block contact), void fill interlock (4 cored system with contractor gravel-filled cores), and a 1/2" bond for joint dispersion. Semma wall, with an integrated coin on every layer, makes a great solution to the raised patio quandary: building a structural wall and topping it with a parapet (free-standing wall).