Components which form and then become part of finished concrete walls are a promising development in the cast in place concrete industry. A California firm has developed what it calls the "Component System" of concrete units; they are paired blocks each 24 inches long and available in 4-, 6-, and 8-inch heights. Wire ties 3/16 inches in diameter connect the pairs, the length of the ties depending on the wall thickness. The units form face shells which can be laid up dry or with mortar, and between which ready mixed concrete is placed to complete a solid wall. The 6- to 24- inch thick monolithic core provides excellent waterproofing. Standard units are used for subterranean walls, retaining walls, flood control channels and shear walls. For architectural finishes, smooth and split face, fluted and scored splits and curved splits are available and can be variously paired to create different inner and outer face finishes on the same wall. The sandblasting of standard units creates texture and exposes the lightweight aggregate. Split units come in eight standard colors. The component system is already at work. At the Tishman Company Airport Center in Los Angeles, architect T.Y. Lin used the system to form 70 foot high, 16 inch thick, 5000 psi shear walls for a 7 story parking structure. The use of fluted split-face components, which combined forming and veneering, resulted in an estimated 30 percent saving in cost. Because the components are usually erected from the inside of the wall space after the placement of reinforcing steel, the system is especially useful in areas with limited maneuvering space. Stripping involves removing strongbacks and snapping ties; sacking and patching are eliminated. Use of the component system usually improves cost control and frees the general contractor to concentrate on administration, supervision, and quality control.