Quad-lock units are shipped flat and assembled onsite. They offer three different insulation values: R22, R32, and R40. Plastic furring strips are molded into the EPS foam to make drywall or exterior siding installation easier. The corners (outside and inside) are 90-degree steel angles, which mount on each row. The angle can be changed so that walls can come together at any angle. www.quad-lock.com