A 6 Inch x 16 Inch 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 Inch bond for joint dispersion. Semma wall, with an integrated corner 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).