The Cambridge Sigma Wall System is built to the highest standards in height, texture, color and ease of use. The Sigma system was designed from contractor feedback. Professional Installers asked for a stone that would not hurt their back, a connection system that was simple to use with no pins, a large wall system that matched our Maytrx and Outdoor Living Kits and a wall that looked good in a residential backyard. The Sigma 6 incorporates our patent pending Double Knob System. It installs as delivered with a 6 degree setback, or by knocking off the front set of “break away” knobs to get “near vertical” alignment. The NEW Sigma line includes large cornerstones that create a great looking, strong corner. And as a bonus, every Sigma Stone has the ability to create two “emergency” stub (smaller) corners for that small job.