2021 Entegra Coach Cornerstone 45B, We have this 2021 Entegra Coach Cornerstone 45B on our lot with 43,400 miles, a bath-and-a-half floor plan, rear bath, and outdoor entertainment. Its Spartan K3 chassis and powerful Cummins diesel are paired with the Cornerstone s quiet, smooth ride, residential-quality interior, and premium finishes. The rear-bath layout gives the coach a spacious private suite while the additional half bath adds convenience when entertaining or traveling with guests.